SERUM ALPHA-FETOPROTEIN AND NEURAL-TUBE DEFECTS IN THE 1ST TRIMESTER OF PREGNANCY

As part of the Medical Research Council randomized trial of vitamin su pplementation in the prevention of neural tube defects (NTDs), materna l serum alpha-fetoprotein (AFP) was available for 19 NTD pregnancies. Each of these was matched with four unaffected controls, by maternal a ge, participating centre, and duration of sample storage. The samples came from women whose gestational age ranged from 6 to 14 completed we eks. The median AFP level in the affected pregnancies was 1.2 multiple s of the median value in unaffected pregnancies of the same gestationa l age (95 per cent confidence interval (CI) 0.83-1-59). This confirmed the view that serum AFP measurement is of no practical value in the d etection of NTDs in the first trimester of pregnancy. The study also s howed that folic acid supplementation, used as a method of preventing NTDs, had no effect on the concentrations of maternal serum AFP up to 14 weeks of pregnancy.