Advertisement

Questionnaire results on exposure characteristics of pregnant women participating in the Japan Environment and Children Study (JECS)

  • Miyuki Iwai-Shimada
  • Shoji F. Nakayama
  • Tomohiko Isobe
  • Takehiro Michikawa
  • Shin Yamazaki
  • Hiroshi Nitta
  • Ayano Takeuchi
  • Yayoi Kobayashi
  • Kenji Tamura
  • Eiko Suda
  • Masaji Ono
  • Junzo Yonemoto
  • Toshihiro Kawamoto
  • the Japan Environment and Children’s Study Group
Open Access
Research article

Abstract

Background

The Japan Environment and Children’s Study (JECS) is a nation-wide birth cohort study investigating environmental effects on children’s health and development. In this study, the exposure characteristics of the JECS participating mothers were summarized using two questionnaires administered during pregnancy.

Methods

Women were recruited during the early period of their pregnancy. We intended to administer the questionnaire during the first trimester (MT1) and the second/third trimester (MT2). The total number of registered pregnancies was 103,099.

Results

The response rates of the MT1 and MT2 questionnaires were 96.8% and 95.1%, respectively. The mean gestational ages (SDs) at the time of the MT1 and MT2 questionnaire responses were 16.4 (8.0) and 27.9 (6.5) weeks, respectively. The frequency of participants who reported “lifting something weighing more than 20 kg” during pregnancy was 5.3% for MT1 and 3.9% for MT2. The Cohen kappa scores ranged from 0.07 to 0.54 (median 0.31) about the occupational chemical use between MT1 and MT2 questionnaires. Most of the participants (80%) lived in either wooden detached houses or steel-frame collective housing. More than half of the questionnaire respondents answered that they had “mold growing somewhere in the house”. Insect repellents and insecticides were used widely in households: about 60% used “moth repellent for clothes in the closet,” whereas 32% applied “spray insecticide indoors” or “mosquito coil or an electric mosquito repellent mat.”

Conclusions

We summarized the exposure characteristics of the JECS participants using two maternal questionnaires during pregnancy.

Keywords

Birth cohort Epidemiology Exposure Japan Environment and Children’s Study JECS 

Abbreviations

JECS

Japan Environment and Children’s Study

MT1

First trimester

MT2

Second/third trimester

Background

The Japan Environment and Children’s Study (JECS) is a nation-wide birth cohort study initiated in 2011. JECS aims to investigate relationships between environmental factors and children’s health and development by recruiting 100,000 expectant mothers [1, 2, 3]. In JECS, children are followed from before birth to 13 years old. The exposures during the prenatal period were assessed using self-administered questionnaires and biological samples collected from the mothers during the first trimester, during the second/third trimester, and after delivery. Postnatal exposures were assessed mainly using questionnaires administered to the mothers every 6 months after birth [1].

Exposure assessment during the prenatal and postnatal period in a birth cohort study is critical to investigate the effect of the environment on children’s health because their developing organs are susceptible to various environmental factors [4]. Many birth cohort studies have been conducted aiming to illustrate the environmental effects on children’s health, including the Danish National Birth Cohort [5], the Norwegian Mother and Child Cohort Study (MoBa) [6, 7], Generation R in the Netherlands [8] and the Mothers’ and Children’s Environmental Health study in South Korea [9]. In JECS, the exposure assessment is based on four approaches: (1) questionnaires, (2) biomonitoring, (3) environmental measurements, and (4) simulation models [2, 3]. The current leading risk factors for the global disease burden are high blood pressure, tobacco smoking including second-hand smoke, household air pollution, and diet. Moreover, worldwide, the contribution of different risk factors to the disease burden has changed substantially, with a shift away from the risks of communicable diseases in children toward those of non-communicable diseases in adults [10]. At the same time, the causation of many chronic diseases and developmental disorders is poorly understood still. For example, the development and exacerbation of asthma can be associated with the complex interactions between environmental, social, and lifestyle factors (e.g., ambient air quality, house dust, mold, and smoking) as well as genetic and epigenetic factors [11]. Therefore, we should assess as many environmental exposures as possible in a birth cohort study instead of using a “one-exposure-one-health-effect” approach [12]. Not all exposures can be measured by biomonitoring or environmental monitoring. For some exposures, e.g., occupational history, daily consumer products, and dwelling condition, we had to rely on questionnaire for data collection. Since we had not found any standardized exposure questionnaire, we developed our own questionnaire for the use in JECS. Thus, it is important for us to characterize JECS exposure questionnaire data for the later use in the analysis of the association between environmental factors and children’s health. To our knowledge, this is the first to compare the responses of approximately 100,000 pregnant women to the exposure questionnaires administered twice during early and mid–late pregnancy periods. In this paper, we describe the environmental exposures of the JECS participants using two maternal questionnaires during pregnancy. We assessed whether pregnant women changed the environmental, lifestyle, and/or workload during pregnancy. The questionnaires were designed to collect information associated with chemical exposures such as dwelling conditions, indoor environment, usage of consumer products, and occupation.

Methods

Study protocol

The JECS study protocol has been published elsewhere [1]. Briefly, 15 Regional Centers were selected to cover wide geographical areas in Japan, located from the north, Hokkaido, to the south, Okinawa [1]. The recruitment took place from January 2011 to March 2014. The eligibility criteria for participants (expecting mothers) were as follows: (1) They should reside in the study areas at the time of the recruitment and are expected to reside continually in Japan for the foreseeable future, (2) expected delivery date should be between 1 August 2011 and mid-2014, and (3) they should be capable to participate in the study without difficulty, i.e., must be able to comprehend the Japanese language and complete the self-administered questionnaire [1]. Self-administered questionnaires completed by the mothers during the first trimester and the second/third trimester were used to collect information on demographic factors, medical and obstetric history, physical and mental health, lifestyle, occupation, environmental exposure at home and in the workplace, housing conditions, and socioeconomic status. The baseline characteristics of the participants have been described elsewhere [2]. In this paper, we report the information about the use of chemical substances by mothers and their work/home environments using questionnaires administered during their pregnancy. We summarized two maternal questionnaires, i.e., the questionnaire intended to be administered during the first trimester (MT1) and that during the second/third trimester (MT2). The MT1 questionnaire collected information on activities and chemical use related to occupation during their pregnancy as exposure metrics. The MT2 questionnaire repeated the questions asked in the MT1 questionnaire and then collected data on their dwelling conditions, the indoor environment, and the use of consumer products (see Supplemental methods). The numbers of responses from the JECS participants for the MT1 and MT2 questionnaires are provided in Fig. 1. The total number of registered pregnancies was 103,099. The response rates of the MT1 and MT2 questionnaire were 96.8% and 95.1%, respectively. The mean gestational ages (SD) at the time of the MT1 and MT2 questionnaire responses were 16.4 (8.0) and 27.9 (6.5) weeks, respectively.
Fig. 1

Environmental exposure data from questionnaires administered to first-trimester and second/third-trimester pregnant women in the Japan Environment and Children’s Study (JECS)

Statistical analysis

The present study was based on the data set jecs-ag-20160424. Categorical variables were reported as a median with interquartile ranges, and categorical variables were the proportion of each questionnaire item to the total number of response. All analyses were performed using JMP version 12.2.0 (SAS Institute Inc., Cary, NC, USA), and P value < 0.0001 was considered statistically significant. We used the McNemar test to assess the differences in proportions between MT1 and MT2. The two questionnaires agreement was assessed using Cohen’s kappa coefficient (kappa scores) [13]. The  kappa score of 0–0.20 was characterized as poor agreement or no agreement beyond chance, 0.21–0.40 as fair, 0.41–0.60 as moderate, 0.61–0.80 as substantial, and 0.81–1.00 as almost perfect agreement [14].

Results

The total number of pregnant women participating in JECS was 103,099. Michikawa et al. [2] have published previously the baseline characteristics of the JECS participants, including age at delivery, marital status, family composition, educational background, household income, and passive smoking (presence of smokers at home). The mean gestational ages (SD) at the time of the MT1 and MT2 questionnaire responses were 16.4 (8.0) and 27.9 (6.5) weeks, respectively.

Table 1 shows the workload characteristics during work and daily life at the current time and at any time since becoming pregnant. The numbers of participants who reported workloads of “lifting something weighing more than 20 kg” and “going in and out of commercial refrigerator or freezer” decreased significantly from the first trimester to the second/third trimester. In contrast, workloads of “exposed to loud noise” and “using manufacturing tools with vibration” increased significantly.
Table 1

Characteristics of workload from workplace, hobbies, and household during pregnancy as reported via two questionnaires of the MT1 and MT2 in the Japan Environment and Children’s Study (JECS)

Variables

MT1

MT2

P

N

%

N

%

 

I have been engaged in at least one of the following activities from nos. 1 to 7 after becoming pregnant

 Yes

13,410

14.0

11,306

11.8

< 0.0001

 No

82,070

86.0

84,174

88.2

 

1. Lifting objects that weigh more than 20 kg

 Yes

5078

5.3

3744

3.9

< 0.0001

 No

90,402

94.7

91,736

96.1

 

2. Exposed to loud noise

 Yes

3353

3.5

3597

3.8

< 0.0001

 No

92,127

96.5

91,883

96.2

 

3. Going in and out of commercial refrigerator or freezer

 Yes

2646

2.8

2091

2.2

< 0.0001

 No

92,834

97.2

93,389

97.8

 

4. Working in a hot place that makes one sweat

 Yes

1841

1.9

1719

1.8

0.0078

 No

93,639

98.1

93,761

98.2

 

5. Using organic solvent

 Yes

1508

1.6

1583

1.7

0.0288

 No

93,972

98.4

93,897

98.3

 

6. Handling powder dust

 Yes

810

0.8

850

0.9

0.1211

 No

94,670

99.2

94,630

99.1

 

7. Using manufacturing tools with vibration

 Yes

417

0.4

565

0.6

< 0.0001

 No

95,063

99.6

94,915

99.4

 

P values are by McNemar test. The questionnaire intended to be administered during the first trimester (MT1) and that during the second/third trimester (MT2)

N number of valid responses

Table 2 shows the frequencies of workload characteristics after becoming pregnant as reported in MT2. The frequency of “lifting something weighing more than 10 kg (including a child),” “using a tool/equipment or riding a vehicle with a strong vibration,” “going in and out of a commercial refrigerator or freezer,” and “working in a hot place that makes one sweaty” more than once a month were 67%, 1.6%, 4.5%, and 0.3%, respectively.
Table 2

Workload characteristics after becoming pregnant as reported via second/third trimester (MT2) questionnaire in the Japan Environment and Children’s Study (JECS)

Variables

N

%

Frequency of lifting something weighing more than 10 kg (including a child) after becoming pregnant

97,587

 

 Never

32,133

32.9

 1–3 times a month

17,251

17.7

 1–4 times a week

15,582

16.0

 5 times a week or more

32,621

33.4

Living or working in a noisy environment after becoming pregnant

97,502

 

 No

87,260

89.5

 Yes

10,242

10.5

Frequency of working sometime between 10 p.m. and dawn after becoming pregnant

97,491

 

 Never

89,394

91.7

 1–3 times a month

4614

4.7

 1–4 times a week

3002

3.1

 5 times a week or more

481

0.5

Frequency of working in a hot place that makes one sweaty after becoming pregnant

97,472

 

 Never

89,385

91.7

 1–3 times a month

3979

4.1

 1–4 times a week

3059

3.1

 5 times a week or more

1049

1.1

Frequency of going in and out of a commercial refrigerator or freezer after becoming pregnant

97,396

 

 Never

93,039

95.5

 1–3 times a month

1506

1.6

 1–4 times a week

1967

2.0

 5 times a week or more

884

0.9

Frequency of using a tool/equipment or riding a vehicle with a strong vibration after becoming pregnant

97,453

 

 Never

95,911

98.4

 1–3 times a month

939

1.0

 1–4 times a week

383

0.4

 5 times a week or more

220

0.2

N number of valid responses, MT2 questionnaire administered to second/third-trimester pregnant women

Table 3 summarizes the occupational use of chemicals after becoming pregnant. Using a questionnaire similar to those used in MT1 and MT2 (for details see Additional file 1), Cohen’s kappa scores ranged from 0.07 to 0.54 (median 0.31). The kappa scores demonstrated mostly fair (between 0.21 and 0.4) to moderate (between 0.41 and 0.6) agreement between MT1 and MT2 except for the use of mercury and engine oil (poor, kappa scores up to 0.2).
Table 3

Frequency of the occupational use of chemicals for more than half a day during pregnancy (MT1 and MT2 questionnaires)

 

MT1

MT2

N

%

%

Kappa scores

Anti-cancer drug (not including your own remedy)

N = 63,576

 No

98.7

98.8

0.54

 1–3 times a month

0.8

0.9

 1–6 times a week

0.4

0.3

 Everyday

< 0.1

0.1

Lead-free solder

N = 63,388

 No

99.7

99.7

0.54

 1–3 times a month

0.1

0.1

 1–6 times a week

0.1

0.2

 Everyday

0.1

0.1

Any products containing lead like solder

N = 63,388

 No

99.7

99.7

0.45

 1–3 times a month

0.2

0.2

 1–6 times a week

0.1

0.1

 Everyday

0.1

0.1

Formalin, formaldehyde

N = 63,584

 No

99.2

99.2

0.44

 1–3 times a month

0.5

0.5

 1–6 times a week

0.3

0.2

 Everyday

0.1

0.1

Microbes

N = 63,399

 No

99.6

99.6

0.44

 1–3 times a month

0.2

0.2

 1–6 times a week

0.2

0.1

 Everyday

0.1

0.1

General anesthetic for surgery at hospital

N = 63,611

 No

99.2

99.1

0.42

 1–3 times a month

0.4

0.5

 1–6 times a week

0.3

0.3

 Everyday

0.1

0.1

Photo copying machine, laser printer

N = 64,895

 No

70.6

66.1

0.39

 1–3 times a month

8.1

11.4

 1–6 times a week

14.2

15.2

 Everyday

7.1

7.3

Radiation, radioactive substances, isotopes

N = 63,385

 No

98.1

98.5

0.38

 1–3 times a month

0.9

0.7

 1–6 times a week

0.8

0.5

 Everyday

0.3

0.2

Medical sterilizing disinfectant

N = 63,931

 No

88.5

86.8

0.37

 1–3 times a month

3.3

5.3

 1–6 times a week

6.0

5.8

 Everyday

2.3

2.0

Dyestuffs (hair coloring)

N = 62,560

 No

93.4

90.8

0.32

 1–3 times a month

5.5

8.0

 1–6 times a week

0.6

0.7

Everyday

0.4

0.5

Permanent marker

N = 64,471

 No

70.3

60.5

0.30

 1–3 times a month

15.8

23.6

 1–6 times a week

11.1

13.2

 Everyday

2.8

2.7

Paint

N = 63,569

 No

80.0

72.9

0.29

 1–3 times a month

10.2

15.5

 1–6 times a week

7.8

9.1

 Everyday

2.4

2.5

Chromium, arsenic, cadmium

N = 63,386

 No

99.9

99.9

0.28

 1–3 times a month

< 0.1

< 0.1

 1–6 times a week

< 0.1

< 0.1

 Everyday

< 0.1

< 0.1

Organic solvents

N = 63,471

 No

92.9

91.1

0.27

 1–3 times a month

5.4

7.2

 1–6 times a week

1.4

1.4

 Everyday

0.3

0.3

Chlorine bleach, germicide

N = 64,016

 No

81.1

73.7

0.27

 1–3 times a month

13.2

19.7

 1–6 times a week

4.9

5.8

 Everyday

0.8

0.8

Kerosene, petroleum, benzene, gasoline

N = 63,778

 No

90.2

84.2

0.26

 1–3 times a month

7.7

12.5

 1–6 times a week

2.0

3.2

 Everyday

0.1

0.1

Insecticide

N = 63646

 No

94.3

91.9

0.21

 1–3 times a month

4.8

7.0

 1–6 times a week

0.9

1.0

 Everyday

0.1

0.1

Herbicide

N = 62837

 No

99.4

98.9

0.19

 1–3 times a month

0.6

1.1

 1–6 times a week

< 0.1

< 0.1

 Everyday

< 0.1

< 0.1

Engine oil

N = 63519

 No

99.0

99.2

0.18

 1–3 times a month

0.7

0.6

 1–6 times a week

0.2

0.2

 Everyday

0.1

0.1

Mercury

N = 63,288

 No

99.7

99.4

0.07

 1–3 times a month

0.3

0.5

 1–6 times a week

< 0.1

< 0.1

 Everyday

< 0.1

< 0.1

Agricultural chemical not listed above or unidentified

N = 64,388

 No

99.8

No data

 

 1–3 times a month

0.1

 1– 6 times a week

< 0.1

 Everyday

< 0.1

Other chemical substances

N = 64,313

 No

99.1

No data

 

 1–3 times a month

0.2

 1–6 times a week

0.4

 Everyday

0.3

The questionnaire intended to be administered during the first trimester (MT1) and that during the second/third trimester (MT2)

N number of valid responses

Table 4 presents the dietary habits during pregnancy as reported on the MT2 questionnaire. Frequency of eating “fast foods,” “retort pouch foods,” “instant noodles, soups, or other foods packed in plastic cups that can be cooked by pouring hot water,” and “canned foods” more than once a week were 15%, 23%, 21%, and 7%, respectively. Frequency of “eating pre-packed foods sold at convenience stores, supermarkets or box lunch shops,” “eating out at a restaurant or eating place,” and “eating frozen foods” more than once a week were 38%, 46%, and 33%, respectively.
Table 4

Dietary habits during pregnancy for breakfast, lunch, or dinner during the last month (MT2)

 

N

%

Eating out at a restaurant or eating place

97,528

 

 Less than once a week

52,962

54.3

 1–2 times a week

40,545

41.6

 3–4 times a week

3261

3.3

 5–6 times a week

601

0.6

 Everyday

159

0.2

Eating pre-packed foods sold at convenience stores, supermarkets or box lunch shops

97,505

 

 Less than once a week

60,850

62.4

 1–2 times a week

27,797

28.5

 3–4 times a week

6485

6.7

 5–6 times a week

1798

1.8

 Everyday

575

0.6

Eating frozen foods

97,381

 

 Less than once a week

65,068

66.8

 1–2 times a week

22,767

23.4

 3–4 times a week

7313

7.5

 5–6 times a week

1663

1.7

Everyday

570

0.6

Eating retort pouch foods

97,284

 

 Less than once a week

75,387

77.5

 1–2 times a week

20,012

20.6

 3–4 times a week

1668

1.7

 5–6 times a week

170

0.2

 Everyday

47

< 0.1

Eating instant noodles, soups, or other foods packed in plastic cups that can be cooked by pouring hot water

97,277

 

 Less than once a week

77,380

79.5

 1–2 times a week

17,758

18.3

 3–4 times a week

1869

1.9

 5–6 times a week

213

0.2

 Everyday

57

0.1

Fast-food intake (e.g., French fries, pizza, donuts)

97,367

 

 Less than once a week

82,699

84.9

 1–2 times a week

13,845

14.2

 3–4 times a week

736

0.8

 5–6 times a week

71

0.1

 Everyday

16

< 0.1

Eating canned foods

96,915

 

 Less than once a week

89,919

92.8

 1–2 times a week

6662

6.9

 3–4 times a week

288

0.3

 5–6 times a week

32

< 0.1

 Everyday

14

< 0.1

N Number of valid responses

Table 5 presents the household environment characteristics such as dwelling condition, air conditioning, cleanup, and mobile phone use during pregnancy collected via the MT2 questionnaire. Most of the participants (80%) lived in either wooden detached houses or steel-frame collective housing. The proportion of the respondents living in a housing that was over 20 years old was 35%. More than half of the questionnaire respondents answered that they had “mold growing somewhere in the house,” with the bathroom being the most frequent site of mold. Wooden floors (covered by carpets, tiles, or no covering) were present in 78% of the residences. As for household cleaning, 92% of the participants had been vacuuming more than once a week. The proportion of participants who did not have a mobile phone was 0.1–0.2%.
Table 5

Household environment characteristics during pregnancy (MT2)

Category

Variables

N

Median

%

 

(25th–75th percentiles)

 

Dwelling condition and material

Type of residence

97,315

  

 Wooden detached house

40,269

 

41.4

 Steel-frame detached house

6190

 

6.4

 Wooden multiple-dwelling house/apartment

12,042

 

12.4

 Steel-frame multiple-dwelling house/apartment

37,861

 

38.9

 Others

953

 

1.0

Age of house/apartment building

97,238

  

 < 1 year

5432

 

5.6

 1 ≦ year < 3

10,920

 

11.2

 3  ≦ year < 5

9152

 

9.4

 5 ≦ year < 10

14,903

 

15.3

 10 ≦ year < 20

22,610

 

23.3

 20 years ≦

24,576

 

25.3

 Unknown

9672

 

9.9

Number of years living in the current place of residence (years)

94,899

3 (1–5)

 

Floor living on/number of floors in the apartment building

63,509/67,230

2 (1–3)/2 (2–4)

 

Number of rooms in the house/apartment

97,293

3 (3–5)

 

Size of the floor space of the house/apartment (m2)

40,321

67 (50–100)

 

House renovation/interior finishing after getting pregnant

97,242

  

 Yes (%)

3076

 

3.2

Living in an all-electric house/building

97,276

  

 Yes (%)

18,317

 

18.8

Small refuse incinerator on the premises of home

97,408

  

 Yes, but it is no longer used (%)

1298

 

1.3

 Yes, it is used still (%)

2632

 

2.7

Use of a water purifier on a water faucet

97,427

  

 Yes (%)

27,539

 

28.3

Mold

Mold growing somewhere in the house

96,853

  

 Yes (%)

60,946

 

62.9

Number of responses

98,051

  

 Kitchen (yes, %)

10,869

 

11.1

 Living room (yes, %)

2020

 

2.1

 Mother’s bedroom (yes, %)

5306

 

5.4

 Other bedroom (yes, %)

1122

 

1.1

 Bathroom (yes, %)

57,252

 

58.4

 Lavatory (yes, %)

4278

 

4.4

 Other place (yes, %)

2886

 

2.9

Pet

Having a pet currently

97,538

  

 Yes (%)

22,483

 

23.1

Number of responses

98,051

  

 Cat (yes, %)

6852

 

7.0

 Bird (yes, %)

682

 

0.7

 Dog (kept in- and outside of residence, yes, %)

13,597

 

13.9

 Hamster (yes, %)

1018

 

1.0

 Turtle (yes, %)

1166

 

1.2

 Others (yes, %)

4076

 

4.2

Air conditioning

Appliance mainly used to cool rooms in the house/apartment

97,618

  

 Air conditioner

70,702

 

72.4

 Electric fan

24,223

 

24.8

 Others

281

 

0.3

 Nothing

2412

 

2.5

Use of a humidifier during the last year

97,634

  

 Yes (%)

56,469

 

57.8

Use of a dehumidifier/dehumidifying function of an air conditioner during the last year

97,564

  

 Yes (%)

58,808

 

60.3

Use of an air-cleaning device

97,632

  

 Yes (%)

50,235

 

51.5

Heating appliance used in the living room during winter (yes, %)

92,257

  

 Yes (%)

91,587

 

99.3

Type of heating equipment in living room

98,051

  

 Kerosene heater/kerosene fan heater

48,454

 

49.4

 Gas heater/gas fan heater

7800

 

8.0

 Kerosene/gas heater (with a chimney or an exhaust pipe that reaches outside of house)

1514

 

1.5

 Air conditioner/steam heater/oil heater

53,741

 

54.8

 Electric “kotatsu” (a table with an electric heater underneath, with a quilt)/electric heater/electric carpet/other electric heating equipment

58,347

 

59.5

 Central heating/floor heating

5831

 

5.9

 Charcoal/briquette “kotatsu” or “hibachi” (Japanese heating appliance using charcoal as fuel)

669

 

0.7

 Other equipment

2404

 

2.5

Use of any equipment to heat a bed during winter

96,376

  

 Yes (%)

30,262

 

31.4

Type of heating equipment in bed

98,051

  

 Electric “anka” (bed warmer)

2969

 

3.0

 Electric blanket

12,608

 

12.9

 Hot water bottle

16,351

 

16.7

 Other equipment

1800

 

1.8

Cleaning

Materials covering the flooring of the living room

97,475

  

 Tatami (Japanese straw floor covering)

11,285

 

11.6

 Carpet on tatami

8853

 

9.1

 Flooring/wooden flooring/tiles

34,574

 

35.5

 Carpet on flooring/wooden flooring/tiles

40,990

 

42.1

 Other

1773

 

1.8

Frequency of cleaning the floor of the living room with a vacuum cleanera

97,616

  

 Everyday

17,156

 

17.6

 A few times a week

42,918

 

44.0

 Once a week

29,605

 

30.3

 1–2 times a month

5784

 

5.9

 A few times a year

915

 

0.9

 Almost never or never

1238

 

1.3

Frequency of cleaning the floor of the bedroom with a vacuum cleanera

97,617

  

 Everyday

10,824

 

11.1

 A few times a week

38,693

 

39.6

 Once a week

34,392

 

35.2

 1–2 times a month

10,371

 

10.6

 A few times a year

1718

 

1.8

 Almost never or never

1619

 

1.7

Frequency of cleaning the “futon” (Japanese mattress and blanket for bedding) with a vacuum cleanera

97,451

  

 A few times a week

3797

 

3.9

 Once a week

10,763

 

11.0

 1–2 times a month

16,369

 

16.8

 A few times a year

12,190

 

12.5

 Almost never or never

54,332

 

55.8

Frequency of airing the “futon” (Japanese mattress and blanket for bedding)a

97,446

  

 A few times a week

8595

 

8.8

 Once a week

23,081

 

23.7

 1–2 times a month

36,214

 

37.2

 A few times a year

18,216

 

18.7

 Almost never or never

11,340

 

11.6

Use of anti-mite covers for “futon” or bedding after getting pregnant

96,946

  

 Yes (%)

7767

 

8.0

Outdoor time

Spending time outdoors (hours per day)

93,944

1.0 (1.0–2.0)

 

Mobile phone

Talk time (per day)

97,648

  

 I do not have a mobile phone

144

 

0.1

 None

10,011

 

10.3

 Less than 10 min

69,381

 

71.1

 For 10–60 min

15,722

 

16.1

 More than 1 h

2390

 

2.4

Number of emails sent and received (per day)

97,606

  

 I do not have a mobile phone

154

 

0.2

 None

2009

 

2.1

 Less than 10 times

83,153

 

85.2

 More than 10 times

12,290

 

12.6

N number of responses

aAverage throughout the year

Table 6 shows the use of household chemicals during pregnancy (MT2). Most of the participants used a deodorizer or an air freshener, especially in the lavatory. Insect repellents and insecticides were used widely in households: about 60% used “moth repellent for clothes in the closet,” whereas 32% applied “spray insecticide indoors” or “mosquito coil or an electric mosquito repellent mat.” About 40% of the participants had used “medicated soap or antibacterial soap,” “cosmetics with strong perfume or a fragrance,” and “nail polish” at least once since becoming pregnant. The incidence of “coloring or perming hair at a beauty salon” during pregnancy was 50%. Combined with the frequency of “coloring or perming hair at home,” the results indicate that most subjects carried out hair treatments during pregnancy.
Table 6

The use of household chemicals during pregnancy (MT2)

Variables

N

%

Frequency of refueling a car with gasoline at a self-service gas station

97,672

 

 Everyday

147

0.2

 4–6 times a week

258

0.3

 2–3 times a week

2354

2.4

 Once a week

8957

9.2

 1–3 times a month

31,912

32.7

 Less than once a month

19,518

20.0

 Never

34,526

35.3

Use of a deodorizer or an air freshener

 Lavatory

97,531

 

 Yes (%)

82,658

84.8

 Living room or bedroom

97,495

 

  Yes (%)

55,267

56.7

Use of a moth repellent for clothes in the closet

97,513

 

 Yes, continuously

21,041

21.6

 Yes, sometimes

36,626

37.6

 Never

39,846

40.9

Use of a spray insecticide indoors

96,799

 

 Yes (%)

30,843

31.9

Frequency of using a spray insecticide indoors

31,676

 

 Everyday

572

1.8

 A few times a week

3490

11.0

 Once a week

1962

6.2

 1–3 times a month

6368

20.1

 Less than once a month

19,284

60.9

Use of a mosquito coil or an electric mosquito repellent mata

97,187

 

 Yes (%)

30,897

31.8

Frequency of using a mosquito coil or electric mosquito repellent mata

31,282

 

 Everyday

8986

28.7

 A few times a week

10,943

35.0

 Once a week

2175

7.0

 1–3 times a month

4193

13.4

 Less than once a month

4985

15.9

Use of a liquid insecticide for maggot and mosquito larva

97,618

 

 Yes (%)

710

0.7

Frequency of using a liquid insecticide for maggot and mosquito larva

706

 

 Everyday

27

3.8

 A few times a week

66

9.3

 Once a week

56

7.9

 1–3 times a month

139

19.7

 Less than once a month

418

59.2

Use of an herbicide or a gardening pesticide in a garden, balcony, or farm

97,425

 

 Yes (%)

8600

8.8

Frequency of using an herbicide or a gardening pesticide in a garden, balcony, or farm

8534

 

 Everyday

83

1.0

 A few times a week

201

2.4

 Once a week

211

2.5

 1–3 times a month

1363

16.0

 Less than once a month

6676

78.2

Spraying insect repellent on clothes or putting lotion on skin

97,152

 

 Yes (%)

23,829

24.5

Frequency of spraying insect repellent on clothes or putting lotion on skin

24,127

 

 Everyday

517

2.1

 A few times a week

4701

19.5

 Once a week

2134

8.8

 1–3 times a month

5592

23.2

 Less than once a month

11,183

46.4

Use of smoke insecticide indoors

97,500

 

 Yes (%)

6578

6.7

Use of a waterproof spray on clothes or shoes

97,468

 

 Yes (%)

11,005

11.3

Use of medicated soap or antibacterial soap

97,339

 

 Yes (%)

41,178

42.3

Use of a body deodorant

97,430

 

 Yes (%)

32,951

33.8

Use of cosmetics with strong perfume or a fragrance

97,588

 

 Quite often

2737

2.8

 Sometimes

14,613

15.0

 Rarely

19,465

19.9

 Never

60,773

62.3

Manicuring or using nail polish

97,608

 

 Quite often

5647

5.8

 Sometimes

18,313

18.8

 Rarely

14,332

14.7

 Never

59,316

60.8

Use of hair coloring products (e.g., hair dye) or perm solutions at home

97,616

 

 Quite often

1246

1.3

 Sometimes

11,801

12.1

 Rarely

9185

9.4

 Never

75,384

77.2

Coloring or perming hair at a beauty salon

97,585

 

 Quite often

3167

3.2

 Sometimes

28,750

29.5

 Rarely

17,100

17.5

 Never

48,568

49.8

Use of sunscreen

97,635

 

 Quite often

31,144

31.9

 Sometimes

27,038

27.7

 Rarely

9622

9.9

 Never

29,831

30.6

Using drug for treatment of scabies or lice

97,613

 

 Yes (%)

558

0.6

N number of valid responses

aContinuously for more than a few hours

Discussion

We developed an in-house exposure questionnaire for the use in JECS since there were no standardized ones available. Almost two identical questionnaires were administered during pregnancy. The exposure data included dwelling conditions, indoor environment, daily life consumer product uses, and occupation. To our knowledge, this is the first of its kind in Japan to characterize over 100,000 pregnant women’s exposure data by the questionnaire. The mean gestational age (SD) at the time of the MT1 questionnaire responses was 16.4 (8.0), which means about half of the participants responded the MT1 questionnaire during the second-trimester period of pregnancy or later. We intended to recruit the participants in early pregnancy but did not restrict to be in the first trimester. Some of the participants were registered at their mid to late pregnancy. When we exclude the responses from the mothers who responded during their gestational ages greater than 16 weeks from the MT1 questionnaire data analysis, the results were similar to those presented in Table 1 (data not shown). The timing of the questionnaire response must be taken into account when researchers use the MT1 questionnaire data for later analysis.

Most of the participants had little occupational exposure to chemicals during pregnancy, while 30–40% of the participants reported the use of personal care products and household pesticide application. Of the participants, 20–30% had consumed convenience foods such as fast foods and retort pouch foods more than once a week within the month prior to the survey, suggesting exposure to chemicals in preservatives or food-packaging materials such as phthalates and bisphenols. Phthalates and bisphenols are suspected endocrine disrupters and have been adversely associated with child health. This information can be used not only to analyze the association between environmental factors and children’s health but also in the future planning of the JECS exposure assessment using biomonitoring.

The Danish National Birth Cohort reported that heavy object lifting was associated with an increased risk of preterm birth in a dose–response manner [15]. Although no exposure–response relationship was observed for fetal death, Mocevic et al. [16] found an increased risk of stillbirth (fetal death ≥ 22 gestational weeks) among those who lifted more than 200 kg/day. In the Danish National Birth Cohort, 16,604 women (26.4%) carried heavy loads (> 20 kg) at work and 475 women (2.9%) lifted more than 1000 kg per day [15]. The Labor Standards Act protects pregnant Japanese women aged ≥ 18 years from tasks that involve heavy object lifting (continuing work, > 20 kg; intermittent work, > 30 kg). In JECS, only 5078 (5.3%) women in the MT1 questionnaire and 3744 (3.9%) women in the MT2 questionnaire lifted loads greater than 20 kg at work (Table 1), though most women in JECS lifted loads greater than 10 kg (including a child) (Table 2).

Various case-control studies have shown the relationship between maternal occupational exposure to solvents and some subtypes of malformations, mostly oral clefts [17, 18, 19, 20]. Significant associations were also reported between maternal exposure to solvents and cardiac malformations [21, 22] and neural tube defects [20]. A review of the results of 49 studies showed that maternal occupational exposure to chemicals (lead and pesticides) was associated with time to pregnancy [23]. Snijder et al. [24] observed in the Netherlands (the Generation R Study) that maternal occupational exposure to polycyclic aromatic hydrocarbons, phthalates, alkylphenolic compounds, and pesticides influenced adversely several domains of fetal growth (fetal weight). In JECS, the occupational use of insecticides, organic solvents, and metals (sum of chromium, arsenic and cadmium, lead, and mercury) more than once a month was reported by 7.1%, 5.8%, and 0.6% of the participants, respectively (Table 3). These frequencies were slightly higher than those in the Generation R Study (n = 4680) in which the prevalence of maternal occupational use of pesticides, organic solvents, and metals were 0.5%, 4.7%, and 1.1%, respectively [24]. With the exception of mercury, occupational exposure to these chemicals was more prevalent in the JECS participants than in the Generation R participants.

Though exposure information obtained from questionnaires could be considered also an important variable, there are few validated standard questionnaire sets. As shown in Table 3, the kappa-coefficients demonstrate mostly fair to moderate agreement between the MT1 and MT2 questionnaires. Since all kappa scores resulted in < 0.61, it suggested that pregnant women could change the chemical use under occupation during pregnancy.

The National Health and Nutrition Survey of Japan [25] reported that the frequency of eating out at a restaurant was 25.1% in total women, 47.3% in women 20–29 years old, and 40.4% in women 30–39 years old. The survey reported also that the frequency of eating pre-packed foods was 39.4% in total women more than 20 years old. In JECS, the frequencies of eating out and eating pre-packed foods more than once a week were 45.7% and 37.6%, respectively. This result is similar to that of the National Health and Nutrition Survey in Japan, indicating that this part of the questionnaire is valid also.

The 2013 Housing and Land Survey of Japan reported that the proportions of wooden housing and non-wooden, such as steel-frame, housing were 58% and 42%, respectively [26]. The JECS results were similar to those of that survey with wooden and non-wooden dwellings reported by 54% and 45% of participants, respectively. In 1981, the Building Standards Act of Japan was revised to enforce new earthquake-resistance standards. The proportion of housing built after 1981 was 64.9% in the national survey (2013), while that of housing less than 20 years of age was 64.8% in JECS. The mean number of rooms and dwelling area in the national survey (2013) were 4.59 rooms and 94.42 m2 per house, respectively. The mean number of rooms and dwelling area in JECS were 3.89 rooms and 82.32 m2 per house, respectively. These results showed that the JECS participants lived in smaller and relatively newer houses compared with respondents to the national survey (2013).

In the questionnaire-based maternal environmental exposure assessment (n = 987) of the INTERGROWTH-21st Project, the rate of household pesticide application was 7.1% (70/987) in respondents from Brazil, China, India, Italy, Kenya, Oman, UK, and the USA [27]. In JECS, the rates of maternal use of moth repellent for clothes, indoor insecticide spray, mosquito coils/mats, liquid insecticides, smoke insecticides, and herbicides were 59%, 32%, 32%, 0.7%, 6.7%, and 8.8%, respectively. People in Japan appear to use more types of pesticides and to use them at a higher rate than people in the abovementioned countries. This indicates the importance of biomonitoring of pesticide chemicals in JECS.

There are some limitations of the JECS exposure assessment questionnaires. Firstly, the self-administered questionnaires were developed in-house by the JECS Programme Office and did not go through any validation process using biological or environmental measurements. Much of the exposure data could only be obtained using questionnaires; the accuracy and reliability of which could not be evaluated. However, some of our results were similar to those of national surveys on such topics as dwelling conditions and dietary habits; accordingly, we assumed that these parts of our questionnaires, at least, were somewhat reliable. The other topics had not been studied previously in Japan in either national surveys or scientific publications. To our knowledge, therefore, these results constitute the first report on the exposure status of pregnant women in Japan. Secondly, we investigated the two questionnaires reliability by administering nearly identical questionnaires in MT1 and MT2. However, there were subtle differences in how the questions were expressed in the MT1 and MT2 questionnaires (for details see Additional file 1), which may have affected the responses. In a future study, we plan to verify the questionnaire as thoroughly as possible using quantitative instruments such as biomonitoring and environmental measurements. Lastly, there were some extreme values observed among the questionnaire responses, e.g., 99 years for the “number of years living in the current place of residence,” 91/83 as “the floor living on/number of floors in the apartment building,” 93 for the “number of rooms in the house/apartment,” and 999 m2 for the “size of the floor space of the house/apartment.” Such values were observed in less than 0.01% of cases. We did not exclude these possible outliers from the analysis presented in this paper since there was no way for us to verify the accuracy of these responses.

This result will be used to design future JECS exposure assessments with biomonitoring. The questionnaire data will also be used to investigate the associations between environmental factors and children’s health and development when data comes available. Some parts of the questionnaire will be validated using biomonitoring data. Such questionnaire items are of great importance for other epidemiological and exposure studies since there are few validated exposure questionnaires. The validate questionnaire can also be used for a national biomonitoring program as a tool to collect exposure source information.

Conclusions

We characterized the environmental exposures of the JECS participants using two maternal questionnaires. Most of the mothers had little occupational exposure to chemicals during pregnancy. The household use of pesticides was more frequent in JECS than in studies in other countries. It will also be used to investigate the associations between environmental factors and children’s health in the future.

Notes

Acknowledgements

We would like to express our gratitude to all the JECS study participants. We sincerely express our appreciation to the co-operating health care providers. We gratefully acknowledge Dr. Hiroshi Satoh (Food Safety Commission, Cabinet Office, Tokyo, Japan) who was the former principal investigator of JECS.

Members of the JECS group, as of April 2018 (principal investigator, Toshihiro Kawamoto) were as follows: Yukihiro Ohya (Medical Support Center for JECS, National Centre for Child Health and Development, Tokyo, Japan), Reiko Kishi (Hokkaido Regional Center for JECS, Hokkaido University, Sapporo, Japan), Nobuo Yaegashi (Miyagi Regional Center for JECS, Tohoku University, Sendai, Japan), Koichi Hashimoto (Fukushima Regional Center for JECS, Fukushima Medical University, Fukushima, Japan), Chisato Mori (Chiba Regional Center for JECS, Chiba University, Chiba, Japan), Shuichi Ito (Kanagawa Regional Center for JECS, Yokohama City University, Yokohama, Japan), Zentaro Yamagata (Koshin Regional Center for JECS, University of Yamanashi, Yamanashi, Japan), Hidekuni Inadera (Toyama Regional Center for JECS, University of Toyama, Toyama, Japan), Michihiro Kamijima (Aichi Regional Center for JECS, Nagoya City University, Nagoya, Japan), Takeo Nakayama (Kyoto Regional Center for JECS, Kyoto University, Kyoto, Japan), Hiroyasu Iso (Osaka Regional Center for JECS, Osaka University, Osaka, Japan), Masayuki Shima (Hyogo Regional Center for JECS, Hyogo College of Medicine, Nishinomiya, Japan), Yasuaki Hirooka (Tottori Regional Center for JECS, Tottori University, Yonago, Japan), Narufumi Suganuma (Kochi Regional Center for JECS, Kochi University, Nankoku, Japan), Koichi Kusuhara (Fukuoka Regional Center for JECS, Kyushu University, Kitakyushu, Japan), and Takahiko Katoh (South Kyushu/Okinawa Regional Center for JECS, Kumamoto University, Kumamoto, Japan).

Funding

The Japan Environment and Children’s Study was funded by the Ministry of the Environment, Japan. The Ministry of the Environment does not ever content of this article. The findings and conclusions of this article are solely the responsibility of the authors and do not represent the official views of the above government agency.

Availability of data and materials

It is not possible to share the raw research data publicly since data privacy could be compromised. Data are unsuitable for public deposition due to ethical restrictions and legal framework of Japan. It is prohibited by the Act on the Protection of Personal Information (Act No. 57 of 30 May 2003, amendment on 9 September 2015) to publicly deposit the data containing personal information. Ethical Guidelines for Medical and Health Research Involving Human Subjects enforced by the Japan Ministry of Education, Culture, Sports, Science and Technology and the Ministry of Health, Labour and Welfare also restricts the open sharing of the epidemiologic data.

Authors’ contributions

SN, SY, MO, JY, KT, ES, HN, TK, and JECS group designed and conducted the survey. MI, SN, TM, and AT performed the statistical analysis and interpretation of the results and drafted the manuscript. TM, TI, YK, HN, and JECS group critically reviewed the manuscript. All authors read and approved the final version of the manuscript as submitted.

Ethics approval and consent to participate

The study protocol was approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies as well as the ethics committees of all participating institutions. All the participants provided written informed consent.

Consent for publication

Not applicable

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary material

12199_2018_733_MOESM1_ESM.pdf (126 kb)
Additional file 1: Supplementary information about questionnaire items for Tables 1 to 6. (PDF 126 kb)

References

  1. 1.
    Kawamoto T, Nitta H, Murata K, Toda E, Tsukamoto N, Hasegawa M, et al. Rationale and study design of the Japan environment and children's study (JECS). BMC Public Health. 2014;14:25.CrossRefGoogle Scholar
  2. 2.
    Michikawa T, Nitta H, Nakayama SF, Yamazaki S, Isobe T, Tamura K, et al. Baseline profile of participants in the Japan Environment and Children’s Study (JECS). J Epidemiol. 2018;  https://doi.org/10.2188/jea.JE20170018.CrossRefGoogle Scholar
  3. 3.
    Michikawa T, Nitta H, Nakayama SF, Ono M, Yonemoto J, Tamura K, et al. The Japan Environment and Children’s Study (JECS): a preliminary report on selected characteristics of approximately 10 000 pregnant women recruited during the first year of the study. J Epidemiol. 2015;25:452–8.CrossRefGoogle Scholar
  4. 4.
    WHO. Principles for evaluating health risks in children associated with exposure to chemicals. Geneva: World Health Organization; 2006.Google Scholar
  5. 5.
    Olsen J, Melbye M, Olsen SF, Sorensen TI, Aaby P, Andersen AM, et al. The Danish National Birth Cohort--its background, structure and aim. Scand J Public Health. 2001;29:300–7.CrossRefGoogle Scholar
  6. 6.
    Magnus P, Irgens LM, Haug K, Nystad W, Skjaerven R, Stoltenberg C, et al. Cohort profile: the Norwegian Mother and Child Cohort Study (MoBa). Int J Epidemiol. 2006;35:1146–50.CrossRefGoogle Scholar
  7. 7.
    Magnus P, Birke C, Vejrup K, Haugan A, Alsaker E, Daltveit AK, et al. Cohort Profile Update: the Norwegian Mother and Child Cohort Study (MoBa). Int J Epidemiol. 2016;45:382–8.CrossRefGoogle Scholar
  8. 8.
    Jaddoe VW, van Duijn CM, van der Heijden AJ, Mackenbach JP, Moll HA, Steegers EA, et al. The Generation R Study: design and cohort update until the age of 4 years. Eur J Epidemiol. 2008;23:801–11.CrossRefGoogle Scholar
  9. 9.
    Park B, Choi EJ, Ha E, Choi JH, Kim Y, Hong YC, et al. A study on the factors affecting the follow-up participation in birth cohorts. Environ Health Toxicol. 2016;31:e2016023.CrossRefGoogle Scholar
  10. 10.
    Lim SS, Vos T, Flaxman AD, Danaei G, Shibuya K, Adair-Rohani H, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380:2224–60.CrossRefGoogle Scholar
  11. 11.
    Martinez FD. Genes, environments, development and asthma: a reappraisal. Eur Respir J. 2007;29:179–84.CrossRefGoogle Scholar
  12. 12.
    Vrijheid M. The exposome: a new paradigm to study the impact of environment on health. Thorax. 2014;69:876–8.CrossRefGoogle Scholar
  13. 13.
    Cohen J. A coefficient of agreement for nominal scales. Educational and Psychological Measurement. 1960;20:37–46.CrossRefGoogle Scholar
  14. 14.
    Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33:159–74.CrossRefGoogle Scholar
  15. 15.
    Runge SB, Pedersen JK, Svendsen SW, Juhl M, Bonde JP, Nybo Andersen AM. Occupational lifting of heavy loads and preterm birth: a study within the Danish National Birth Cohort. Occup Environ Med. 2013;70:782–8.CrossRefGoogle Scholar
  16. 16.
    Mocevic E, Svendsen SW, Jorgensen KT, Frost P. Bonde JP occupational lifting, fetal death and preterm birth: findings from the Danish National Birth Cohort using a job exposure matrix. PLoS One. 2014;9:e90550.CrossRefGoogle Scholar
  17. 17.
    Laumon B, Martin JL, Collet P, Bertucat I, Verney MP, Robert E. Exposure to organic solvents during pregnancy and oral clefts: a case-control study. Reprod Toxicol. 1996;10:15–9.CrossRefGoogle Scholar
  18. 18.
    Lorente C, Cordier S, Bergeret A, De Walle HE, Goujard J, Ayme S, et al. Maternal occupational risk factors for oral clefts. Occupational Exposure and Congenital Malformation Working Group. Scand J Work Environ Health. 2000;26:137–45.CrossRefGoogle Scholar
  19. 19.
    Chevrier C, Dananche B, Bahuau M, Nelva A, Herman C, Francannet C, et al. Occupational exposure to organic solvent mixtures during pregnancy and the risk of non-syndromic oral clefts. Occup Environ Med. 2006;63:617–23.CrossRefGoogle Scholar
  20. 20.
    Desrosiers TA, Lawson CC, Meyer RE, Richardson DB, Daniels JL, Waters MA, et al. Maternal occupational exposure to organic solvents during early pregnancy and risks of neural tube defects and orofacial clefts. Occup Environ Med. 2012;69:493–9.CrossRefGoogle Scholar
  21. 21.
    Gilboa SM, Desrosiers TA, Lawson C, Lupo PJ, Riehle-Colarusso TJ, Stewart PA, et al. Association between maternal occupational exposure to organic solvents and congenital heart defects, National Birth Defects Prevention Study, 1997-2002. Occup Environ Med. 2012;69:628–35.CrossRefGoogle Scholar
  22. 22.
    Tikkanen J, Heinonen OP. Cardiovascular malformations and organic solvent exposure during pregnancy in Finland. Am J Ind Med. 1988;14:1–8.CrossRefGoogle Scholar
  23. 23.
    Snijder CA, te Velde E, Roeleveld N, Burdorf A. Occupational exposure to chemical substances and time to pregnancy: a systematic review. Hum Reprod Update. 2012;18:284–300.CrossRefGoogle Scholar
  24. 24.
    Snijder CA, Roeleveld N, Te Velde E, Steegers EA, Raat H, Hofman A, et al. Occupational exposure to chemicals and fetal growth: the Generation R Study. Hum Reprod. 2012;27:910–20.CrossRefGoogle Scholar
  25. 25.
    Ministry of Health, Labour and Welfare of Japan. National Health and Nutrition Survey of Japan. 2015. http://www.mhlw.go.jp/file/04-Houdouhappyou-10904750-Kenkoukyoku-Gantaisakukenkouzoushinka/kekkagaiyou.pdf [in Japanese]Google Scholar
  26. 26.
    Statistic Bureau, Ministry of Internal Affairs and Communications of Japan. Housing and Land Survey of Japan. 2013. http://www.e-stat.go.jp/SG1/estat/NewListE.do?tid=000001063455, http://www.stat.go.jp/data/jyutaku/2013/pdf/nihon00.pdf [in Japanese]Google Scholar
  27. 27.
    Eskenazi B, Bradman A, Finkton D, Purwar M, Noble JA, Pang R, et al. A rapid questionnaire assessment of environmental exposures to pregnant women in the INTERGROWTH-21st Project. BJOG. 2013;120(Suppl 2):129–38. vCrossRefGoogle Scholar

Copyright information

© The Author(s). 2018

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • Miyuki Iwai-Shimada
    • 1
  • Shoji F. Nakayama
    • 1
  • Tomohiko Isobe
    • 1
  • Takehiro Michikawa
    • 1
  • Shin Yamazaki
    • 1
  • Hiroshi Nitta
    • 1
  • Ayano Takeuchi
    • 1
    • 2
  • Yayoi Kobayashi
    • 1
  • Kenji Tamura
    • 1
  • Eiko Suda
    • 1
  • Masaji Ono
    • 1
  • Junzo Yonemoto
    • 1
  • Toshihiro Kawamoto
    • 1
    • 3
  • the Japan Environment and Children’s Study Group
  1. 1.Japan Environment and Children’s Study Programme OfficeNational Institute for Environmental StudiesTsukubaJapan
  2. 2.Department of Preventive Medicine and Public HealthKeio UniversityTokyoJapan
  3. 3.Department of Environmental HealthUniversity of Occupational and Environmental HealthKitakyushuJapan

Personalised recommendations