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.