Placental pathology of IVF-conceived dichorionic diamniotic twins after fresh embryo versus frozen-thawed transfer

Introduction: To compare histopathological findings of placentas of dichorionic diamniotic twin pregnancies of in-vitro fertilization (IVF), conceived after fresh embryo transfer (ET) and frozen-thawed ET. Methods: This retrospective study compared dichorionic diamniotic twin IVF pregnancies that resulted in livebirths during 2010–2022. The placental findings were classified according to definitions curated by the 2016 Amsterdam Placental Workshop Group Consensus Statement. A multivariate logistic analysis was constructed to estimate the odds ratios (OR) of placental histopathology abnormal findings, adjusted for maternal age, body mass index and nulliparity. Results: The mean gestational age at birth was lower following fresh ET pregnancies (n = 236) than frozen-thawed ET pregnancies (n = 122) (34.89 vs 35.77 weeks, p = 0.003). For the fresh ET compared to the frozen-thawed ET group, rates were higher of preterm birth (69.5 % vs. 55.7 %, p = 0.011), low birthweight (71.6 % vs 57.4 %, p < 0.001) and very low birthweight (14.2 % vs 9.0 %, p value one sided = 0.029). For the fresh ET compared with the frozen-thawed ET group, the rates were higher of maternal vascular lesions (20.3 % vs. 11.5 %, p = 0.003), placental hemorrhage (12.7 % vs. 7 %, p = 0.021), and villous lesions related to maternal vascular lesions (7.2 % vs. 3.7 %, p value one sided = 0.04). A multivariate logistic analysis showed a higher risk of maternal or neonatal vascular lesions for twin pregnancies after fresh ET than frozen-thawed ET (adjusted OR = 1.91, 95 % CI 1.26–2.92, p = 0.011). Conclusions: Following fresh ET compared to frozen-thawed ET, obstetrical and neonatal outcomes were worse, and the risk of maternal vascular lesions was greater.