Elevated maternal serum alpha-fetoprotein and amniotic fluid alpha-fetoprotein after multifetal pregnancy reduction.

Forty patients underwent fetal reduction at approximately 12 weeks' gestation for multiple pregnancy. Twenty-two had maternal serum alpha-fetoprotein (MSAFP) determinations and all but one was elevated, with a mean value of 9.41 multiples of the median (MOM). A total of 53 amniotic fluid specimens were evaluated for AFP; 25% were elevated above 2.0 MOM and one sample was positive for acetylcholinesterase. None of these elevations were associated with a neural tube defect, although two neural tube defects were detected by other means. Routine MSAFP is not recommended for patients with multifetal pregnancy reduction.