Persistent antiphospholipid antibodies do not contribute to adverse pregnancy outcomes

To determine whether women with persistent aPL (>12 weeks apart on at least two separate occasions) without a history of thrombosis or adverse pregnancy outcome had the same adverse pregnancy outcomes as those with obstetric APS or unmatched controls.

This was a case-control study between 2005 and 2011 where we identified 73 women with persistent aPL and coincidentally the same number with obstetric APS. Unmatched controls were identified from low-risk clinics (ratio 1:4). Women with multiple pregnancies, fetal anomalies, SLE, thrombotic APS and other thrombophilias were excluded.

Cases and controls were demographically similar, with the exception of younger controls with fewer medical comorbidities. aPL profiles were similar between aPL and APS. In women with aPL, risk of APS-type complications (odds ratio 1.3; 95% CI 0.6, 2.9) and birthweight distribution (median birthweight on a customized centile was 50.8, interquartile range 26.4-68.9; P < 0.05) were similar to controls. These findings persisted even after adjustment for maternal age and medical comorbidities.

Women with persistent aPL on aspirin had pregnancy outcomes that were similar to controls. These data suggest that in the absence of other risk factors, women with aPL do not need intense antenatal surveillance or modified management in pregnancy.