Risk factors for non‐previa placenta accreta spectrum in pregnancies conceived through frozen embryo transfer during a hormone replacement cycle in Japan

Abstract

Abstract Purpose Non‐previa placenta accreta spectrum (PAS) is associated with assisted reproductive technology (ART), particularly frozen embryo transfer during hormone replacement therapy (HRC‐FET). We especially aimed to evaluate the prevalence and risk factors for non‐previa PAS in HRC‐FET pregnancies. Methods Overall, 279 women who conceived through ART at three ART facilities and delivered at a single center were included in this retrospective study. Data regarding endometrial thickness at embryo transfer, previous histories, and type of embryo transfer—HRC‐FET, frozen embryo transfer during a natural ovulatory cycle (NC‐FET), and fresh embryo transfer (Fresh‐ET)—were collected. Univariable logistic regression analyses were conducted. Results The prevalence of non‐previa PAS was 27/192 (14.1%) in the HRC‐FET group and 0 (0.0%) in both the NC‐FET and Fresh‐ET groups. Significantly high odds ratio [95% confidence interval] of non‐previa PAS was associated with a history of artificial abortion (6.45 [1.98–21.02]), endometrial thickness <8.0 mm (6.11 [1.06–35.12]), resolved low‐lying placenta (5.73 [2.13–15.41]), multiparity (2.90 [1.26–6.69]), polycystic ovarian syndrome (2.62 [1.02–6.71]), and subchorionic hematoma (2.49 [1.03–6.04]). Conclusions A history of artificial abortion, endometrial thickness <8.0 mm, and resolved low‐lying placenta may help in antenatal detection of a high‐risk population of non‐previa PAS in HRC‐FET pregnancies.

Keywords

• assisted reproductive technology
• frozen embryo transfer
• hormone replacement cycle
• non‐previa placenta accreta spectrum
• placenta accreta spectrum