Lack of association between antiphospholipid antibodies and first-trimester spontaneous abortion: prospective study of pregnancies detected within 21 days of conception

Objective: To determine the role of antiphospholipid antibodies and anticardiolipin antibodies in first-trimester losses, addressing experimental pitfalls that preclude excluding the possibility that these antibodies reflect merely the selection bias of studying couples only after they have already experienced losses. Design: Given that retrospective studies cannot exclude the possibility that such antibodies arise as a result of the fetal death, blood samples were obtained either before pregnancy or very early in pregnancy. Sera were obtained within 21 days of conception. Setting: Multicenter university-based hospitals (National Institute of Child Health and Human Development collaborative study). Patient(s): Subjects for the current study were 93 women who later experienced pregnancy loss (48 diabetic; 45 nondiabetic), matched 2:1 with 190 controls (93 diabetic and 97 nondiabetic) who subsequently had normal live-born offspring. Intervention(s): Sera from these 283 women were analyzed for antiphospholipid antibodies by enzyme immunoassay. In 260 of the 283 women (87 with pregnancy losses; 173 with live-born infants), sera were also available to perform assays for anticardiolipin antibodies by enzyme immunoassay. Main Outcome Measure(s): Pregnancy losses. Result(s): No association was observed between pregnancy loss and the presence of antiphospholipid antibodies or anticardiolipin antibodies. Levels of antiphospholipid antibodies were 6-19 PL/mL in 62.4% of the pregnancies that ended in losses and greater than or equal to 20 PL/mL in 5.4%; among pregnancies resulting in live-born infants, the percentages were 56.8% and 6.8%, respectively. Of the pregnancies that ended in a loss, 5.7% had anticardiolipin antibodies greater than or equal to 16 GPL/mL, compared with 5.2% of those ending in a live birth. Conclusion(s): This prospective study suggests that anticardiolipin antibodies and antiphospholipid antibodies are not associated with an increased risk for first-trimester pregnancy loss. (C) 1998 by American Society for Reproductive Medicine.