PREDICTING PREGNANCY OUTCOME FROM THE DEGREE OF MATERNAL SERUM ALPHA-FETOPROTEIN ELEVATION

OBJECTIVE: To determine if a correlation exists between the level of m aterial serum alpha-fetoprotein (MSAFP) elevation and the rate of adve rse pregnancy outcome, to examine the timing of pregnancies ending in fetal or neonatal death, and to develop a protocol for antepartum surv eillance in an effort to prevent these adverse outcomes. STUDY DESIGN: Single-ton pregnancies with a single second-trimester elevated MSAFP greater than or equal to 2.0 multiples of the median (MoM) were eligib le if a targeted ultrasound evaluation (< 24 weeks) ions in agreement with the dates and no fetoplacental anomaly was detected. Three groups were established based on the second-trimester MSAFP elevation: 2.0-2 .49, 2.5-2.99 and greater than or equal to 3.0 MoM. RESULTS: Among the 383 patients enrolled, delivery data were available on 333 infants. S tratified by MSAFP elevations of 2.0-2.49, 2.5-2.99 and greater than o r equal to 3.0 MoM, the rates of adverse pregnancy outcome were: (1) p reterm birth: 14.3%, 15.6%, 20.3%; (2) small for gestational age at bi rth: 7.4%, 11.1%, 22.2%; and (3) perinatal deaths (neonatal and fetal) : 2.6%, 3.3%, 5.6%. Seven pregnancy losses (three neonatal and four fe tal deaths) occurred prior to 28 weeks. Of these seven, six fetuses ex hibited intrauterine growth retardation by 23-26 weeks' gestation, and Jive of six were associated with MSAFP levels greater than or equal t o 2.5 MoM. Four losses (two neonatal and two fetal deaths) occurred af ter 28 weeks. Of these, three involved structurally normal infants wit h normal growth who died after 34 weeks. All three of these pregnancie s exhibited MSAFP elevations < 2.5 MoM. CONCLUSION: In pregnancies wit h an unexplained elevated second-trimester MSAFP, the rate of adverse pregnancy outcomes is increased with higher elevations. Any proposed p rogram to improve pregnancy outcome in patients with unexplained MSAFP elevations must include efforts aimed at preventing preterm delivery, repeat ultrasound at 24-26 weeks to rule our early-onset intrauterine growth retardation in pregnancies with elevations greater than or equ al to 2.5 MoM and fetal biophysical monitoring, even in normally grown fetuses, instituted at 32 weeks to detect fetuses at risk for intraut erine death.