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.
- Birth head circumference
- Birth weight
- Maternal mild hyperphenylalaninemia
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health