The international collaborative study of maternal phenylketonuria: status report 1998

The Maternal Phenylketonuria Study began in 1984 and during the intervening years, 572 pregnancies in hyperphenylalaninemic women and 99 controls and their outcomes have been evaluated. Among hyperphenylalaninemic women who d elivered a live infant, only 15.9% were treated and in metabolic control pr econceptually, however, another 18.4% were in control by 10 weeks. Compared to the results reported by Lenke and Levy in 1980, there is a marked impro vement in outcome with treatment. Microcephaly was unusual in preconceptual ly treated pregnancies with well controlled phenylalanine restricted diets. Even in pregnancies that established control after conception but before t he 8th week, congenital heart disease did not occur in the offspring, howev er, it did occur in 12% of pregnancies not achieving control until after 10 weeks of pregnancy. Conclusion The recommended level of blood phenylalanine during pregnancy is 120- 360 mu mol/l. Best results were obtained by close cooperation between the attending obstetrician and a metabolic team experienced in the care of persons with phenylketonuria.