Hansen AT, et al. - Researchers determined the risk of venous thromboembolism (VTE) in the 12 weeks following early pregnancy loss in pregnancies conceived by IVF. Findings suggest a low VTE risk in the 12 weeks following early pregnancy loss in these pregnancies.

Methods

• Researchers performed a nationwide registry-based cohort study including all Danish IVF pregnancies registered in the Danish IVF Register between 1995 and 2005.
• They did not include women who underwent frozen embryo replacement or oocyte donation.
• All 24,931 IVF treatments leading to pregnancy among 19,260 women were included.
• In this study, 16,701 complete IVF pregnancies, 7567 IVF pregnancies with early pregnancy loss, and 663 IVF pregnancies terminated by late abortion (≥gestational weeks 10) were identified.
• For 12 weeks after termination of pregnancy, women were followed; the absolute risk of VTE was calculated during follow-up with 95% CI.
• They estimated a relative risk estimate via determining the risk ratio for VTE following IVF pregnancies with early loss compared to the VTE risk following complete IVF pregnancies.

Results

• Researchers identified only one case of VTE in the group of early pregnancy loss, none in the late abortion group, and 13 VTE cases in complete IVF pregnancies during the 12 weeks of follow-up.
• They noted the VTE risk per 10 000 pregnancies of 1.3 [0.03–7.4] for IVF pregnancies with early loss and 7.8 [4.1–13.3] for complete pregnancies; the corresponding risk ratio was 0.17 [0.02–1.3]; hence, suggesting a low absolute VTE risk in the 12 weeks following early pregnancy loss in IVF pregnancies.
• A low relative VTE risk was evident in comparison to the VTE risk in early gestation reported for complete IVF pregnancies and for Danish background pregnancies.