Maternal serum and amniotic fluid alpha-fetoprotein as a marker of acute fetal distress in a midtrimester abortion model.

Maternal serum (MS) and amniotic fluid (AF) alpha-fetoprotein (alpha-FP) levels were serially determined in 18 cases of elective midtrimester abortion. Prostaglandin F2alpha (PGF2alpha) and 20% NaCl were used as the abortifacients in 2 groups of 9 patients, respectively. The time from instillation to abortion (IAT) was accurately recorded in all cases. A marked 260-600% increase in MS alpha-FP occurred prior to fetal demise in both groups. Amniotic fluid alpha-FP content remained largely unchanged for the first 6 hours following intraamniotic prostaglandin injection. A 50% INCREASE WAS OBSERVED IN THE AF alpha-FP content in the group with 20% NaCl-induced abortion (after an initial dilutionary drop). The results of this investigation confirm the value of alpha-FP in MS as a marker of impending fetal demise. This rise is not caused by a prior alpha-FP change in the AF. The data suggest a major fetomaternal transplacental route for alpha-FP.