Maternal phenylketonuria: successful outcome in four pregnancies treated prior to conception.

The management of four pregnancies in two phenylketonuric women is described. A successful outcome in these pregnancies is ascribed to the initiation of treatment prior to conception and the maintenance of tight control with serum phenylalanine between 100 and 400 mumol/l throughout the gestation period. A trial of diet is desirable before a decision is made about pregnancy and before contraception is ceased. Close contact must be maintained with female phenylketonurics throughout their reproductive life to ensure that this process is followed.