Method of Delivery and Neonatal Mortality among Very Low Birth Weight Infants in the United States
- 275 Downloads
Objective: To examine the association between method of delivery (primary cesarean section vs. vaginal) and neonatal mortality risk (as well as causes of death) among very low-birth weight first-born infants in the United States. More specifically, to examine this association separately for breech/malpresenting and vertex-presenting infants, while adjusting for selected maternal characteristics, and pregnancy, labor and delivery complications. Methods: The study population was derived from the 1995–1998 birth cohort linked birth/infant death data sets. Binary and multinomial logit regression analyses were performed to assess the relationship in four very low-birth weight categories. Results: Among breech/malpresenting neonates, compared to those delivered vaginally, infants delivered by a primary cesarean section had significantly lower adjusted relative risks of death for all very low-birth weight categories and the decrease in relative risk tended to be larger with each increasing birth weight category. However, for vertex-presenting neonates, results are mixed, suggesting decreased relative mortality risks associated with primary cesarean section, which were significant for 500–749 g, not significant for 750–999 g, and barely significant for 1,000–1,249 g. In contrast, for vertex-presenting neonates weighing 1,250–1,499 g, there was a significantly increased adjusted relative risk associated with primary cesarean section. Differences in cause-specific neonatal mortality by method of delivery and presentation status were also discussed. Conclusions: Primary cesarean section appears to be associated with decreased neonatal mortality risks in each very low-birth weight category for breech/malpresenting infants, but results are mixed for vertex-presenting infants. Causal inferences should be avoided because this was an observational study by design.
KEY WORDS:method of delivery neonatal mortality very low-birth weight.
- 1.US Department of Health and Human Services. Cesarean Childbirth. Report of a consensus development conference sponsored by the National Institute of Child Health and Human Development in conjunction with the National Center for Health Care Technology. September 22–24, 1980. NIH Publication No. 82-2067. October, 1981. US Department of Health and Human Services.Google Scholar
- 2.US Department of Health and Human Services. Healthy People 2000. National health promotion and disease prevention objectives. Washington: Public Health Service, 1990.Google Scholar
- 3.Bottoms SF, Paul RH, Iams JD, Mercer BM, Thom EA, Roberts et al. Obstetric determinants of neonatal survival: Influence of willingness to perform cesarean delivery on survival of extremely low-birth-weight infants. Am J Obstet Gynecol 1997;176:960–6.Google Scholar
- 5.Jonas HA, Lumley JM. The effect of mode of delivery on neonatal mortality in very low birth weight infants born in Victoria, Australia: Caesarean section is associated with increased survival in breech-presenting, but not vertex-presenting infants. Paediatr Perinat Epidemiol 1997;11:181–99.CrossRefPubMedGoogle Scholar
- 10.Kitchen W, Ford GW, Doyle LW, Rickards AL, Lissenden JV, Pepperell RJ, Duke JE. Cesarean section or vaginal delivery at 24 to 28 weeks' gestation: Comparison of survival and neonatal and two-year morbidity. J Am College Obstet Gynecol 1985;66:149–57.Google Scholar
- 11.Cibils LA, Karrison T, Brown L. Factors influencing neonatal outcomes in the very-low-birth-weight fetus (<1,500 grams) with a breech presentation. Am J Obstet Gynecol 1984;171:35–42.Google Scholar
- 17.National Center for Health Statistics. 1995–1998 Birth cohort linked birth/infant death data set. CD ROM series 20, published annually since 1995. Hyattsville, Maryland.Google Scholar
- 18.Mathews TJ, Curtin SC, MacDorman MF. Infant mortality statistics from the 1998 period linked birth/infant death data set. National Vital Statistics Reports 48(12), 2000. US Department of Heath and Human Services, Centers for Disease Control and Prevention, National Center Health Statistics, Hyattsville.Google Scholar
- 19.SAS Institute, Inc. SAS/STAT Software: Changes and enhancements, Release 8.2, Cary, NC, 2000.Google Scholar
- 26.American College of Obstetricians and Gynecologists. Evaluation of Cesarean Delivery. Washington, DC: ACOG, 2000.Google Scholar
- 27.Martin JA, Hamilton BE, Sutton PD, Ventura SJ, Menacker F, Munson ML. Births: Final data for 2002. National vital statistics reports; vol. 52 no. 10. Hyattsville, Maryland: National Center for Health Statistics, 2003.Google Scholar
- 28.MacDorman MF, Martin JA, Mathews TJ, et al. Explaining the 2001–02 infant mortality increase: Data from the linked birth/infant death data set. National vital statistics reports; vol. 53 no. 12. Hyattsville, Maryland: National Center for Health Statistics. 2005.Google Scholar