Fertility treatments (FT) have been associated with an increased risk of thromboembolic complications (TEC). However, whether this excess risk exists for arterial thrombosis and whether it differs by type of ART remains poorly documented.

The objectives were to estimate TEC rates following unsuccessful FT cycle (TC) and FT-related pregnancy, according to type of FT.

Women aged 18–45 years with an FT between 2012 and 2015 were selected in the French health insurance claim database. TC were classified into simple ovulation induction (OI) or ovulation stimulation (OS). All hospitalisations in women with FT, with a diagnosis of venous thromboembolism (VTE) or arterial thrombosis (AT) were identified in the French hospital discharge database. Separate analyses were performed for unsuccessful and successful TC. Poisson regressions were used to estimate incidence rate ratios (IRR) comparing both incidence of TEC following unsuccessful TC versus incidence in all non-pregnant women of same age range, and TEC incidence during FT-related pregnancy versus incidence in spontaneous pregnancy.

During the study period, 280,000 women underwent FT (total of 809,913 TC) with 82,821 FT-related pregnancies. Among unsuccessful TC, 75 VTE and 43 AT were observed. OS TC but not OI TC was associated with a higher risk of VTE compared with the reference group [1.7, 95% CI (1.3–2.3)]. Among FT-related pregnancies, 207 VTE and 35 AT were reported. The IRR adjusted for age and multiple pregnancy showed significant higher rates of VTE and AT during first trimester comparing to spontaneous pregnancy [IRR=3.3, 95% CI (2.2–4.8) and IRR=2.6, 95%CI (1.1–6.5) respectively].

This study highlights the importance of monitoring women undergoing FT, especially OS TC, regardless of pregnancy status. In FT-related pregnancy, the first trimester seems to be a high-risk period for TEC compared with spontaneous pregnancies.