The impact of maternal serum alpha fetoprotein screening on open neural tube defect births in north-east Scotland.

Over the three years period 1980-1982, 18 256 pregnancies in the Grampian Region of N-E Scotland including the islands of Orkney and Shetland were screened for raised levels of maternal serum alpha fetoprotein (MSAFP) in the second trimester. Thirty six cases of fetal open neural tube defect in singletons were detected (18 anencephaly and 18 spina bifida). Four additional cases of open spina bifida were associated with normal MSAFP levels although two of these were detected by amniotic fluid AFP measurement when amniocentesis was carried out because of previous NTD history. A further three cases of open spina bifida and two of anencephaly occurred in unscreened pregnancies. The MSAFP screening programme alone was thus instrumental in reducing the birth incidence of open neural tube defects by 36 out of 45 cases (80 per cent) in singletons.