Prevalence of elevated anticardiolipin antibodies in pregnant women with unexplained elevations of alpha-fetoprotein.

The goal was to determine what proportion of pregnant women with unexplained elevations of maternal serum alpha-fetoprotein (MSAFP) have increased levels of anticardiolipin antibodies (ACA), and if this might explain the increased prevalence of adverse pregnancy outcomes. Maternal serum alpha-fetoprotein levels of 12,295 pregnant women were evaluated at 15-19.5 gestational weeks. Elevated readings (> 2.5 MOM) were identified in 190 women (1.5%) and 86 (0.7%) of these had unexplained causes. Specimens (80) were recovered and ACA levels for cardiolipin were determined using enzyme-linked immunosorbant assay. Positive IgG ACA were identified in 10 out of 80 cases (12.5%) of elevated MSAFP; 3 out of 80 cases (3.8%) had positive IgM ACA. The control women with normal MSAFP levels had positive IgG ACA in 3 of 86 cases (3.5%) and 1 of 86 cases (1.2%) for IgM. Women with increased MSAFP and positive ACA had infants with an average birth weight of 2684 +/- 889 g compared to 2793 +/- 847 g in women with increased MSAFP and normal ACA. No significant differences in IgG ACA were found in pregnant women with unexplained elevated MSAFP (10/80, 12.5%) compared to women with normal MSAFP (3/86, 3.5%). As expected, lower birth weight was identified in women who had elevated MSAFP (2738 +/- 868 g) vs. women with normal MSAFP 3181 +/- 1082 g (P = 0.004), independent of ACA positivity.