Maternal phenylketonuria: low phenylalaninemia might increase the risk of intra uterine growth retardation.

International audienceBACKGROUND: Malformations and mental retardation in the offspring of women with Phenylketonuria (PKU) can be prevented by maintaining maternal blood Phenylalanine (PHE) within a target range (120-300 μmol/L) through a PHE-restricted diet. In a former French study, a high and unexpected proportion of intra uterine growth retardation (IUGR) has been reported. Guidelines have been proposed to all French centres caring for maternal PKU since 2002. OBJECTIVE: To confirm IUGR and investigate its causes. The other goals were to assess the follow-up of these pregnancies based on the new guidelines and the pertinence of these recommendations. DESIGN: Clinical, biological and ultrasound data of all pregnancies in PKU women in France, from 2002 to 2007 were retrospectively analyzed. RESULTS: Data from 115 pregnancies in 86 women with PKU were collected. Ninety percent of women had been informed of the risk of maternal PKU in the absence of a strict diet during pregnancy, 88 % of women had started a diet before conception, and 45 % of infants were born small for gestational age (birth length and/or weight ≤-2 SD). PHE intakes were lower in the group with IUGR from the fifth to the eighth month of pregnancy and duration of time spent at