Observational Study of Pregnant Women With a Previous Spontaneous Abortion Before the 10th Gestation Week With and Without Antiphospholipid Antibodies

Abstract

The Sapporo criteria-related definition commonly used for diagnosis of the antiphospholipid syndrome (APS) associates the occurrence of thrombotic and/or obstetrical events with persistently positive antiphospholipid antibodies (aPL-Ab), including lupus anticoagulant (LAC), anticardiolipin IgG (aCL-G) or IgM, and/or anti-b2-glycoprotein I IgG or IgM antibodies. Criteria used to define the purely obstetrical clinical subtype of the APS syndrome include the aPLs listed above plus a fetal loss later than 10-weeks gestation, 3 or more unexplained consecutive embryonic losses before the 10th week gestation, or eclampsia or features of placental insufficiency requiring the preterm birth before 34 weeks of a morphologically normal child. Some investigators have questioned the serological criteria associated with this form of APS and have suggested that the aCL-G, anticardiolipin IgM, and anti-b2-glycoprotein I IgM measurements should be excluded. To determine the effects of the various aPL-Ab subtypes on pregnancy outcome, the investigators prospectively monitored women who had had an unexplained embryonic loss during their first pregnancy and were undergoing their untreated second pregnancy. They selected women who did not have APS; any hormonal abnormalities; or inflammatory, infectious, or malignant diseases; and who had normal parental karyotypes; the pregnancy outcomes of 142 women who tested positive for at least 1 of the 5 classical aPL-Abs were compared with those of 142 control women who were confirmed to be aPL-Abs negative. Compared with the women without aPL-Abs, the aPL-Ab-positive women experienced more clinical complications during their second pregnancy, including pregnancy loss (of which the majority were embryonic losses), preeclampsia, placental abruption, and intrauterine fetal growth restriction. The presence of LAC alone (type IIa aPL-Ab positivity) was associated with the highest risk of recurrent embryonic loss and intrauterine growth restriction. Positive tests for combinations of aPL-Ab (type I aPL-Ab positivity) were associated with the highest risk of late complications, placental abruption, and preeclampsia. A finding of anti-b2-glycoprotein I IgM positivity had no apparent diagnostic clinical relevance. These findings demonstrate that among women with a first unexplained pregnancy loss before the 10th week of gestation, those who are aPL-Abs positive have a higher risk of complications in their next pregnancy, including embryonic loss, preeclampsia, placental abruption, and intrauterine growth restriction, than women who are aPL-Abs negative. These findings suggest that the aPL-Ab LAC, aCL-G or IgM, and anti-b2-glycoprotein I IgG are helpful in identifying patients at increased risk of an adverse outcome, whereas anti-b2-glycoprotein I IgM has questionable diagnostic value.