Pregnancy outcomes after increasing maternal serum alpha-fetoprotein levels.

Five hundred sixty women among 35,787 screened had an initial maternal serum alpha-fetoprotein (MSAFP) of 2.5 or more multiples of the median. They were divided into three groups: group 1, 2.5-2.9; group 2, 3.0-3.9; and group 3, over 4.0 multiples of the median. These groupings determined the relationship to adverse pregnancy outcome, defined as fetal death, fetus with significant anomalies, and prematurity/growth retardation. The overall risk of adverse outcome after an initial elevation was 38%, after excluding pregnancies with incorrect dates or multiple gestations with levels below 4.5 multiples of the median: 27, 39, and 45% in groups 1, 2, and 3, respectively. This risk rose to 86% for levels over 6.0 multiples of the median. There was a significant positive correlation between abnormalities and death detected with ultrasound and amniocentesis and those indicated by increasing MSAFP levels: 10, 20, and 31% in groups 1, 2, and 3, respectively. After normal ultrasound and amniocentesis studies, there was a trend toward increasing risks for fetal death after 20 weeks between groups 2 and 3 (5 and 11%), but not for growth retardation/prematurity (12, 17, and 13%). After an elevated MSAFP, the overall risk of a late pregnancy complication after normal ultrasound and amniocentesis was 22%: 19, 23, and 25% in groups 1, 2, and 3, respectively. This figure increased to 67% for levels above 6.0 multiples of the median.