European Journal of Pediatrics

, Volume 155, Supplement 1, pp S20–S25 | Cite as

Maternal non-phenylketonuric mild hyperphenylalaninemia

  • H. L. Levy
  • S. E. Waisbren
  • D. Lobbregt
  • E. Allred
  • A. Leviton
  • R. Koch
  • W. B. Hanley
  • B. Rouse
  • R. Matalon
  • F. de la Cruz


Unlike maternal phenylketonuria (PKU) which produces severe birth defects when untreated during pregancy, maternal non-PKU mild hyperphenylalaninemia (MHP) has a less severe impact but whether it is benign or may have long-term consequences for offspring has been unclear. From an international survey of maternal MHP we obtained information about 86 mothers (blood phenylalanine (Phe) 150–720 µmol/1), their 219 untreated pregnancies and 173 offspring. Spontaneous fetal loss and congenital anomalies were no more frequent than normally expected. Median Z-scores for birth length and birth head circumference and offspring IQ (100), however, were significantly lower for maternal Phe > 400 µjnol/1 than for maternal Phe <400 µmol/1, in which the median offspring IQ was 108. Data on maternal MHP from the prospective Maternal PKU Collaborative Study (MPKUCS) are as yet incomplete but seem to be conforming to the general pattern of the international survey. We conclude that maternal blood Phe levels above 400 µmol/1 in maternal MHP are associated with lower birth measurements and slightly lower offspring IQ. It would seem that dietary intervention to lower the maternal Phe levels to below 400 µmol/l might be indicated in maternal MHP pregnancies with the higher blood Phe levels.

Key words

Maternal mild hyperphenylalaninemia Phenylketonuria Birth weight length Birth head circumference IQ 







non-PKU mild hyperphenylalaninemia


Maternal PKU Collaborative Study


general cognitive index


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Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • H. L. Levy
    • 1
    • 2
  • S. E. Waisbren
    • 1
    • 2
  • D. Lobbregt
    • 1
  • E. Allred
    • 1
  • A. Leviton
    • 1
    • 2
  • R. Koch
    • 3
  • W. B. Hanley
    • 4
  • B. Rouse
    • 5
  • R. Matalon
    • 6
  • F. de la Cruz
    • 7
  1. 1.I. C. Smith 106Children’s HospitalBostonUSA
  2. 2.Medical SchoolBostonUSA
  3. 3.Children’s Hospital Los AngelesLos AngelesUSA
  4. 4.Hospital for Sick ChildrenTorontoCanada
  5. 5.University of Texas at GalvestonGalvestonUSA
  6. 6.Children’s HospitalMiamiUSA
  7. 7.National Institute of Child Health and Human Development NIHBethesdaUSA

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