Does cryopreservation of embryos increase risk of placenta accreta?

A small study by investigators from Harvard University suggests that cryopreserved embryo transfer (CET) is a strong independent risk factor for placenta accreta in women undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI). The findings, presented at the American Society for Reproductive Medicine 70^th Annual Meeting, showed an even stronger association in cases of accreta with complications.

Data on 1,569 women who had delivered at least one viable infant at ≥24 weeks’ gestation and underwent a Day 3 or Day 5 transfer at a single institution between 2005 and 2011 were included in the analysis. Among them, 52 cases of placenta accreta were identified, as confirmed by histology or a clinical finding of an adherent placenta with or without morbid complications such as postpartum hemorrhage, hysterectomy or surgery to remove the placenta. Cases were matched 1:3 by maternal age and history of prior cesarean to IVF/ICSI patients without accreta.

Multivariate analysis resulted in an overall incidence of accreta in the cohort of 3.31% (52/1,569), versus 7.24% (16/221) in the women who had undergone CET. The median age of cases and controls was similar (39.3 versus 39.1). No potential confounders were included in the final model because none were found to change the effect size for CET by more than 10%.

Feature: Euploid single-embryo transfer: The new IVF paradigm

The only significant predictors of accreta were CET (P=.04), prior myomectomy (P<.01), and placenta previa (P<.0001). When the analysis was restricted to only morbid cases of accreta, the effect was strengthened to 2.78 (95% CI 1.11-6.99; P=.03).

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