Maternal phenylketonuria and hyperphenylalaninemia are at present the most disturbing issue in phenylketonuria. Causing an embryopathy and fetopathy compromising growth and resulting in mental retardation, microcephaly, congenital defects and low birth weight. The problem of maternal phenylketonuria and hyperphenylalaninemia is a direct effect of successful newborn screening for phenylketonuria as well as early and consistent dietary treatment. Before the screening was widely introduced most women with phenylketonuria were mentally retarded and only few of them had children. Advantages of the screening for phenylketonuria in one generation can be lost in the next one unless a preventive treatment is maintained in a high proportion of affected women. The proper management of maternal phenylketonuria and hyperphenylalaninemia requires coordinated efforts in many areas, such as: obstetric and antenatal care, dietary treatment, biochemical research and control, psychological assessments, teratogenesis, ethics and counselling. In order to achieve good results in treating women with phenylketonuria and hyperphenylalaninemia and to prevent complications in their offspring, it is recommended to create national phenylketonuria and hyperphenylalaninemia register and to introduce regional programmes of support for the women a risk.

Keywords: phenylketonuria (PKU), maternal phenylketonuria (MPKU), hyperphenylalaninemia (HPA), Pregnancy Outcome, phenylalanine restricted diet