Maternal phenylketonuria: the French survey

Abstract

We report the French experience regarding pregnancies in maternal phenylketonuria (PKU). In 2001, a questionnaire was sent to each referring PKU specialist in the 20 centres of each region of France, collecting reports on 135 pregnancies in 79 women born between 1958 and 1980. The majority of the 135 pregnancies occurred after 1990. A total of 42 women were informed of the risks of untreated pregnancy, while 26 were not informed (no data for 11). A strict diet was achieved in 83% of informed and in 16% of uninformed mothers prior to conception. Healthy offspring were observed in 43% of the 135 pregnancies, spontaneous abortions in 10.4%, elective abortions in 4.4%, therapeutic abortions in 12.6%, and embryopathies (EP) in 21.5%. In 8.1% of cases, the outcomes (in earliest pregnancies) are unknown. The proportion of healthy children increased over time and reached 80% of the pregnancies of informed females. There were seven heart defects, all in cases of EP, but although microcephaly and intrauterine growth retardation (IUGR) were almost constant in EP, we also found nine healthy children with IUGR. A continuum between EP and healthy children is suggested. The anthropometric data of the mothers showed that their body mass index (BMI) distribution was shifted to the left compared to women of the general population. This lower BMI and poor weight gain during pregnancy could contribute to the IUGR observed in normal babies whose mothers received a phenylalanine-restricted diet during pregnancy.

Conclusion: the information and the preconception diet are effective for avoiding embryopathies in maternal phenylketonuria. Nutritional parameters can influence fetal growth and the nutritional state must be closely monitored throughout pregnancies of women with phenylketonuria.