Risk factors and role of low molecular weight heparin in obstetric complications among women with inherited thrombophilia – a cohort study

INTRODUCTION: Although there is a vast literature regarding the association between inherited thrombophilia, obstetric complications and the effect of low molecular weight heparin (LMWH), these are controversial and we have not found publications related to additional risk factors other than thrombophilia. Our objectives were to assess the prevalence of miscarriage, placenta-mediated pregnancy complications and fetal loss in pregnant women with IT, establishing associated risk factors and the effect of LMWH. MATERIALS AND METHODS: A retrospective cohort of pregnant women with IT was formed. Risk factors considered were: high-risk IT, age ≥35 years, body mass index ≥25 and ≥30, assisted reproductive technology, antiphospholipid antibodies, autoimmune disease, first-degree family history of obstetric complications and personal history of venous or arterial thromboembolic disease, the outcomes being M, FL and PMPC. RESULTS AND CONCLUSIONS: Data from 250 pregnancies in 88 women were obtained. There were 112 (45%) Ms, 13 (5.2%) FLs and 25 (10%) PMPCs. High-risk IT was associated with FL (OR = 4.96; 95% CI, 1.42–17.3). Antiphospholipid antibodies and family history of obstetric complications were associated with PMPC (OR = 7.12; 95% CI, 1.89–26.74, OR = 3.88; 95% CI, 1.18–12.78, respectively). The LMWH presented a benefit in the combined outcome (any obstetric complication, OR = 0.25; 95% CI, 0.12–0.54) and M (OR = 0.41; 95% CI, 0.20–0.82). We conclude that obstetric complications are common in women with IT. Antiphospholipid antibodies, family history of obstetric complications and high-risk IT might be additional risk factors. The LMWH has an apparent protective effect against obstetric complications, which is consistent with some previous studies.