The North American collaborative study of maternal phenylketonuria (PKU)

Nationwide neonatal screening for phenylketonuria (PKU) has created an unexpected problem as these women are reaching childbearing age. Surveys have revealed that maternal phenylalanine blood concentrations >1200 μmol/L (≥20 mg/dL) are associated with microcephaly, mental retardation, congenital heart defects, and intrauterine growth retardation among offspring. It is estimated that as many as 3000 hyperphenylalaninemic (HPA) women may be at risk for producing these fetal abnormalities. To examine this problem, the North American maternal PKU Collaborative Study (MPKUCS) has been developed. The Study has been designed to evaluate the efficacy of a phenylalanine-restricted diet in reducing the fetal morbidity associated with maternal HPA. Preliminary findings indicate that phenylalanine restriction should begin before conception for women with PKU planning a pregnancy. Dietary control should maintain average maternal blood phenylalanine levels at 360 μmol/L (6 mg/dL) and should provide adequate calorie, protein, vitamin and mineral intake. Pregnant HPA women who achieved metabolic control after conception but by the tenth week of pregnancy had a better offspring outcome than anticipated.