Antenatal screening for congenital nephrosis in Finland by maternal serum alpha-fetoprotein.

In the Kuopio and North-Karelia districts of Finland 10724 pregnancies were screened for congenital nephrosis by maternal serum alpha-fetoprotein (AFP) measurement. Outcome was known for 10504 (98%) pregnancies, of which 509 (4 X 8%) had a serum AFP level greater than or equal to 2 X 5 multiples of the normal median (MoM) at 15-18 weeks gestation. After exclusion of those women who had a normal serum AFP level (less than 2 X 5 MoM) in a second sample, 'wrong dates' or multiple pregnancy, 267 (2 X 5%) remained with a high serum AFP level. Amniocentesis was carried out in 225 (2 X 1%) and 16 women had an amniotic fluid AFP level greater than 10 SD above the normal mean. In this group there were six fetuses with congenital nephrosis (four confirmed and two suspected), six other serious malformations (including an intrauterine death) and four without obvious abnormality. In the 98% pregnancies followed up there were no infants with congenital nephrosis that had been missed. Babies with congenital nephrosis require permanent hospitalization and have a mean survival of 8 months. In Finland, within certain areas, the birth prevalence is as high as 1 in 2600 per year. In such areas maternal serum AFP measurement appears to be a useful method of screening for congenital nephrosis. The service was also well accepted since 94% of the women with raised serum AFP levels wished to be screened again in a future pregnancy.