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Impact of frozen embryo transfer on placenta accreta and institutional variations
Shunya Sugai1, Takayuki Tatsumi2, Kohei Ogawa2
1Department of Obstetrics and Gynaecology, Niigata University Medical and Dental Hospital, Niigata, Japan.
Research Question:
Does programmed cycle frozen embryo transfer (PC-FET) increase the risk of placenta accreta spectrum (PAS) compared with natural cycle FET (NC-FET), and does this risk vary according to facility-level utilization of PC-FET?
Design:
This nationwide, cross-sectional study analysed 38,973 frozen embryo transfer deliveries identified in the Japanese perinatal registry database (2020-2022), linked to the assisted reproductive technology registry database (2019-2022). The primary exposure was PC-FET versus NC-FET. Facilities were stratified into tertiles based on the proportion of PC-FET (low, medium and high). The primary outcome was PAS, defined as either clinical or pathological. Morbid PAS was defined as PAS accompanied by haemorrhage >2000 ml or managed with balloon tamponade, compression sutures, embolization, or peripartum hysterectomy. OR and 95% CI were estimated with stabilized inverse probability of treatment weighting and multivariable regression.
Results:
PAS occurred in 3.6% and 0.7% of PC-FET and NC-FET deliveries, respectively (OR 5.02, 95% CI 3.87-6.53). Morbid PAS occurred in 1.5% and 0.3% of PC-FET and NC-FET deliveries, respectively (OR 5.36, 95% CI 3.51-8.20). Facilities with a high proportion of PC-FET had a higher risk of PAS (OR 1.36, 95% CI 1.16-1.58) and morbid PAS (OR 1.34, 95% CI 1.07-1.70) compared with facilities with a low proportion of PC-FET.
Conclusions:
This study provides robust evidence that PC-FET increases the risk of PAS. Further research should explore the association between facility variations and the incidence of PAS.
