Purpose: Recent publications suggested that the risk for pre-eclampsia (PE) is higher with frozen-thawed embryo transfers (FETs) compared to fresh transfers (IVF-ETs). These studies were based on old data that reflects outdated practices. In this paper, we wanted to assess the incidence of PE in current assisted reproductive technology (ART) practice.
Methods: In this cohort study, we present the incidence of PE in all births in the province of Ontario, Canada, for the years 2013-2017 for FET, IVF-ET, and natural conceptions (NC). We also compare our findings to previous studies in a meta-analysis that includes over 4 million births.
Results: The results of our study show that contemporary practice of ART results in comparable risk for PE between FET and IVF-ET; however, the risk is higher than NC.
Conclusion: Current ART practice is associated with a lower risk for PE in frozen embryo transfer; this RR can be further attenuated by using ovulatory endometrial preparation for FETs.
Keywords: Assisted reproductive technology; Fresh embryo transfer; Frozen embryo transfer; Hypertensive disorders of pregnancy; Natural conception; Pre-eclampsia.