maternal phenylketonuria in pregnancy

Last reviewed 09/2021

Adult female with PKU in which treatment has ceased may become pregnant. This places even a genetically normal foetus at risk - it is exposed to high levels of phenylalanine, resulting in severe foetal malformation and brain damage. Dietary restrictions should be reintroduced before pregnancy to keep the maternal blood phenylalanine between 120 and 480 umol/l.

Antenatal diagnosis of PKU is not currently available.