Cryopreserved embryo transfer is an independent risk factor for placenta accreta

To explore the association between cryopreserved embryo transfer (CET) and risk of placenta accreta among patients utilizing in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI). Case-control study. Academic medical center. All patients using IVF and/or ICSI, with autologous or donor oocytes, undergoing fresh or cryopreserved transfer, who delivered a live-born fetus at ≥24 weeks of gestation at our center, from 2005 to 2011 (n = 1,571), were reviewed for placenta accreta at delivery. Cases of accreta (n = 50) were matched by age and prior cesarean section to controls (1:3) without accreta. The association between CET and accreta was modeled using conditional logistic regression, controlling a priori for age and placenta previa. Receiver operating characteristic curves were used to determine thresholds of endometrial thickness and peak serum E 2 levels related to accreta. Placenta accreta. Univariate predictors of accreta were non-Caucasian race (odds ratio [OR] 2.85, 95% confidence interval [CI] 1.25–6.47); uterine factor infertility (OR 5.80, 95% CI 2.49–13.50); prior abdominal or laparoscopic myomectomy (OR 7.24, 95% CI 1.92–27.28); and persistent or resolved placenta previa (OR 4.25, 95% CI 1.94–9.33). In multivariate analysis, we observed a significant association between CET and accreta (adjusted OR 3.20, 95% CI 1.14–9.02), which remained when analyses were restricted to cases of accreta with morbid complications (adjusted OR 3.87, 95% CI 1.08–13.81). Endometrial thickness and peak serum E 2 level were each significantly lower in CET cycles and those with accreta. Cryopreserved ET is a strong independent risk factor for accreta among patients using IVF and/or ICSI. A threshold endometrial thickness and a “safety window” of optimal peak E 2 level are proposed for external validation.