Since the late 1980s some publications have proposed that antiphospholipid antibodies (aPL) may have some relationship with infertility, considering reported deleterious effects that aPL exert on trophoblast proliferation and growth. Although not included in current classification criteria for antiphospholipid syndrome, many physicians investigate for aPL in patients with a history of infertility, including antibodies not listed in classification criteria, and most of those patients will receive anticoagulant therapy if any of those antibodies have a result considered positive. A review of literature was conducted searching for studies that investigated the association of aPL and infertility and if aPL positivity alters in vitro fertilization (IVF) outcome. The definition of infertility, routine work-up to exclude other causes of infertility, definition of IVF failure as inclusion criteria and control populations were heterogeneous among studies. Most of them enrolled women over 40 years of age, and exclusion of other confounding factors was also inconsistent. Of 29 studies that assessed aPL positivity rates in infertile women, the majority had small sample sizes, implying a lack of power, and 13 (44.8%) reported higher frequency of aPL in infertile patients compared to controls, but most of them investigated a panel of non-criteria aPL tests, whose clinical significance is highly controversial. Only two studies investigated all three criteria tests, and medium-high titer of anticardiolipin cut-off conforming to international guidelines was used in one study. Considering IVF outcome, there was also disparity in this definition: few studies assessed the live birth rate, others the implantation rate. Of 14 publications that addressed the relationship between aPL and IVF outcome, only two described a detrimental effect of these autoantibodies. In conclusion, available data do not support an association between aPL and infertility, and aPL positivity does not seem to influence IVF outcome. Well-designed clinical studies recruiting women with a clear diagnosis of infertility and a high-risk aPL profile should be performed to test whether clinically relevant aPL do-or not-exert an effect on human fertility.

Pre-eclampsia (PE) is a major cause of maternal mortality and morbidity, perinatal deaths, preterm birth and intrauterine growth restriction. Differential diagnosis with antiphospholipid syndrome (APS) nephropathy and systemic lupus erythematosus (SLE) nephritis during pregnancy is difficult, if not sometimes impossible, as all three diseases may present hypertension and proteinuria. Improvement in diagnosis of PE has also offered new paths for differential diagnosis with other conditions and the analysis of angiogenic (vascular endothelial growth factor, placental growth factor) and antiangiogenic factors (serum soluble fms-like tyrosine kinase 1, soluble endoglin) is promising for differentiation between PE, APS nephropathy and SLE nephritis. This article reviews published studies about those factors in non-pregnant and pregnant patients with APS and SLE, comparing with patterns described in PE.

Evidence from basic science studies supports a causative relationship between antiphospholipid antibodies (aPL) and recurrent early miscarriage (REM) (prior to 10 weeks of gestation). However, human studies have not consistently found a relationship between aPL and REM. Members of the Obstetric Task Force of the 14th International Congress on Antiphospholipid Antibodies performed a literature review of the association of aPL and REM and searched for clinical trials in women with REM who tested positive for aPL. Of the 46 studies that investigated the relationship between aPL and REM, 27 found a positive association, seven found no association, and the remaining 12 papers could not report an association (lack of control group). The main identified problems for such conflicting results were varying definitions of REM (two or three abortions, not necessarily consecutive; different gestational age at which pregnancy losses occurred); analysis of patients with previous fetal death (>10 weeks) in the same group of REM; and different definitions of "positive aPL" (cutoffs not following international recommendations; small number of studies confirmed persistence of positive aPL after six to 12 weeks). The 10 identified randomized trials with proposed treatments for women with REM who test positive for aPL also had heterogeneous inclusion criteria, with only one trial limited to subjects who would meet the current criteria for antiphospholipid syndrome (APS) by both clinical and laboratory criteria. Against this background, we conclude that the association between REM and aPL remains inconclusive and that the findings of treatment trials are at best inconsistent and at worst misleading. More convincing data are critically needed. Studies that identify, or at least stratify, according to international consensus criteria and include standardized core laboratory testing results are crucial if we are to establish an evidence-based association between aPL and REM and treatment recommendations.

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