Maternal phenylketonuria

Elevated maternal phenylalanine levels during pregnancy are teratogenic and may result in growth retardation, significant psychomotor handicaps, and b irth defects in the offspring of unmonitored and untreated pregnancies. Wom en of childbearing age with all forms of phenylketonuria, including mild va riants such as hyperphenylalaninemia, should receive counseling concerning their risks for adverse fetal effects optimally before conceiving. The best outcomes occur when strict control of maternal phenylalanine levels is ach ieved before conception and continued throughout the pregnancy.