Nutrient intake and congenital heart defects in maternal phenylketonuria

Objective: The purpose of this study was to determine whether nutritional components other than high maternal blood phenylalanine levels (≥10 mg/dL) are associated with congenital heart defects in the offspring of women with hyperphenylalaninemia. Study Design: Of the 414 subjects who had live births, 249 women (60.1%) started diet treatment before 8 weeks of gestation and had nutritional assessments and infant outcome data. Maternal phenylalanine levels, protein intake, and the incidence of congenital heart defects were determined. Simple contingency table analysis was done by χ2 and Fisher exact test. Results: A significantly increased incidence of congenital heart defects was observed in offspring of mothers with hyperphenylalaninemia who had an elevated blood phenylalanine level >10 mg/dL at 0 to 8 weeks of gestation and a protein intake of ≤50% of the recommended dietary allowance (P< .0013). Conclusion: An inadequate intake of protein during pregnancy in conjunction with elevated blood phenylalanine levels appear to have an additive effect in the incidence of congenital heart defects in the offspring of women with hyperphenylalaninemia. (Am J Obstet Gynecol 2002;187:441-4.)