Baby of a phenylketonuric mother. Inferences drawn from a single case.

Reports on pregnancy in phenylketonuric women are rare, but fetal brain damage has been well documented and attributed to the mother's biochemical disturbance. Reports on fetal health after the treatment of phenylketonuria (PKU) in pregnancy are even rarer. Since the treatment of PKU girls is often stopped or relaxed at various prepubertal ages, pregnancy may occur soon in apparently normal girls who have high phenylalanine levels and PKU. In view of the scarcity of information, implications are cautiously suggested from the experience gained of one case. More information is needed urgently, not about the effects of PKU alone, but also of hyperphenylalaninaemia. The present case suggests that it is possible for a fetus to escape malformation, brain damage, and growth failure if maternal dietary treatment is good from about the 20th week of gestation. It would be unwise, however, to accept this finding as holding true for all cases.