P-770 Risk factors for placenta accreta spectrum among pregnant women conceived with assisted reproductive technology

Abstract Study question What are the risk factors for placenta accreta spectrum (PAS) among women conceived with assisted reproductive technology (ART)? Summary answer The risk of PAS was associated with elevated estradiol and progesterone levels during COH, and HRT protocol, and abnormal endometrial thickness when preforming FET. What is known already Increasing evidence suggests an association between ART and PAS. Some studies have reported a high rate of diagnosis of PAS after embryo transfer compared to those with spontaneous conception. Despite this, little is known about the detailed risk factors for PAS during the procedures of ART. Study design, size, duration This retrospective case-control study included 1541 pregnant women with live birth conceived ART between 2013 and 2019 in a university hospital. Participants/materials, setting, methods Pregnant women were categorized into case and control group according to the postpartum diagnosis of PAS. The associations between PAS and ART procedures were estimated using multivariate logistic regression, and represented as adjusted odds ratio (aOR) and 95% confidential interval (CI). Main results and the role of chance Among all pregnant women in this study, 118 were delivered with PAS, and 1423 were delivered without PAS. During the procedures of COH and oocytes retrieval, elevated levels of estradiol (aOR=1.03, 95% CI: 1.01-1.06) and progesterone (aOR=1.02, 95% CI: 1.00-1.04) were found to be associated with the risk of PAS. The number of oocytes retrieved over 10 were also found to have an association with PAS (aOR=1.58, 95% CI: 1.05-2.37). Additionally, FET was another risk factor forPAS (aOR=1.93, 95% CI: 1.06-3.51). Among pregnant women with FET, preparing the endometrium using HRT protocol increased the risk of PAS (aOR=2.46, 95% CI: 1.57-3.84). Notably, PAS was also found to have an association with abnormal endometrial thickness after preparing the endometrium, whether too thin (<7mm: aOR=15.90, 95% CI: 4.42-57.21) or too thick (>14mm: aOR=6.56, 95% CI: 1.84-23.45). Limitations, reasons for caution As a hospital-based study, several confounders related to medical procedures have been taken into consideration. However, it is not possible to rule out unknown confounders. Wider implications of the findings Caution is warranted when preforming COH, and endometrial preparation before FET due to the increased risk of PAS after deliveries. Trial registration number NA