The challenge of maternal phenylketonuria screening and treatment.

All newborn infants, male and female, have been screened for phenylketonuria (PKU) since 1961. Medical therapy is generally continued until age 6. The first cohort of treated females reached reproductive age 15 years ago, and new members are joining this cohort annually. This paper reviews the implications of childbearing in women who were treated for PKU as children and are no longer under treatment. Untreated maternal PKU can lead to mental retardation in utero.