Associations between adverse perinatal outcome and serially obtained second- and third-trimester maternal serum alpha-fetoprotein measurements.

Abstract

Our purpose was to determine whether third-trimester maternal serum alpha-fetoprotein predicts adverse perinatal outcome and whether use of both second- and third-trimester maternal serum alpha-fetoprotein enhances the positive predictive value for various abnormal outcomes. A cohort study with obstetric outcome assessed by chart analysis after delivery was performed at Regional Medical Center (Memphis, Tennessee), a hospital staffed by university-based physicians serving a large urban population with many indigent patients. A total of 650 women attending prenatal clinics in the above setting with a singleton pregnancy without a neural tube defect, contributing a maternal blood samples in both the second and third trimesters, and delivered in the above hospital participated. Various pregnancy outcomes were correlated with maternal serum alpha-fetoprotein levels in the second and third trimesters and in both. In the third trimester no significant associations were found between maternal serum alpha-fetoprotein elevations and pregnancy complications. In the second trimester elevation ( > or = 2.0 multiples of the median) were, by contrast, significantly associated with preterm premature rupture of the membranes, preterm birth, and low birth weight. No association was found with certain other complications. When second-trimester data were grouped according to the types of complications occurring in individual women, only preterm premature rupture of the membrane proved statistically significant. Second-trimester but not third-trimester maternal serum alpha-fetoprotein is significantly elevated with preterm premature rupture of the membranes, preterm birth, and low birth weight; in this cohort study no association was found with preeclampsia, oligohydramnios, or polyhydramnios.