Low risk of VTE Following Early Pregnancy Loss in Pregnancies Conceived by IVF

Low risk of venous thromboembolism following early pregnancy loss in pregnancies conceived by IVF

Adapted from Hansen AT, et al. Hum Reprod. 2018;33(10):1968-1972.

Key Takeaway

• There is a low absolute VTE risk in the 12 weeks following early pregnancy loss in IVF
• The relative VTE risk was low for complete IVF pregnancies in comparison to the risk in early gestation

Why This Matters

• During the first trimester of IVF pregnancies that leads to delivery, there is an increased risk of VTE
• This risk is unknown in IVF failed due to early pregnancy loss (implantation failure, missed abortion, or spontaneous or induced abortion before 10 completed gestational weeks)

Study Design

• A nationwide registry-based cohort study including all Danish IVF pregnancies registered in the Danish IVF Register between 1995 and 2005
• Exclusion: Women undergoing frozen embryo replacement or oocyte donation
• Endpoint: Incident VTE (Absolute risk - number of VTEs per 10,000 pregnancies with 95% CI) following IVF pregnancies terminated by either delivery (complete IVF pregnancies) or early IVF pregnancy loss or abortion
• Follow-up: 12 weeks

• The absolute risk of VTE in IVF pregnancies for early loss and for complete pregnancies was 1.3 [0.03–7.4] and 7.8 [4.1–13.3], respectively, with RR of 0.17 ([0.02–1.3]; P=0.08)

The results do not indicate a need for prophylactic anticoagulant therapy in women suffering early IVF pregnancy loss without other risk factors

Limitations

• The study had only a few VTE events available for statistical analyses which limited the precision of estimates
• Failure in ruling out the occurrence of VTE cases not diagnosed at the hospital
• Information on the use of prophylactic LMWH was not available