Antiphospholipid antibodies in predicting adverse pregnancy outcome. A prospective study

To determine if the presence of antiphospholipid antibody (aPL) in healthy pregnant women is associated with adverse pregnancy outcome, including 1) intrauterine fetal loss, 2) maternal pregnancy complications, 3) low birth weight, and 4) low 5-minute Apgar scores.

Prospective cohort study in women with normal pregnancies.

Obstetrics clinic at the University of Colorado Health Sciences Center.

Eligible patients included 451 low-risk, nulliparous pregnant women who came to the obstetrics clinic before 25 weeks gestation; 408 were enrolled and 389 had blood drawn at the first prenatal visit and completed clinical follow-up.

Blood for six aPL measures was drawn at the first prenatal visit and for 239 patients at delivery.

Ninety-five patients (24.4%) had elevated aPL levels by one or more measures at the first prenatal visit: 15.8% of the aPL-positive and 6.5% of the aPL-negative patients experienced fetal loss (relative risk, 2.44; 95% CI, 1.29 to 4.62). However, an elevated IgG anticardiolipin antibody level at the first prenatal visit was the only aPL measurement that was significantly associated with fetal loss (relative risk, 3.5; CI, 1.56 to 8.07). Adjustment for confounding variables decreased the relative risk of aPL for fetal loss slightly, but the difference remained statistically significant. Neither a positive aPL result at the initial visit nor a positive result at delivery was associated with maternal complications of pregnancy, low birth weight, or low Apgar scores.

Patients with elevated aPL levels at their initial prenatal visit had an increase in fetal loss but no increase in maternal pregnancy complications, low birth weight, or low Apgar scores. Immunoglobulin G anticardiolipin antibody was the only single test of aPL significantly associated with fetal loss.