Effect of Parity on Placental Histopathology Features in Singleton Live Births Following IVF

The aim of this study was to evaluate the effect of parity (primipara vs multipara) on the histopathology of the placenta in singleton live births following in vitro fertilization. We conducted a retrospective cohort study evaluating data of all IVF resulted live births from one university affiliated hospital during 2009-2017. All patients had the placenta sent for pathological evaluation. Exclusion criteria were history of miscarriage or elective termination of pregnancy, abnormal uterine cavity findings, previous uterine surgery, in vitro maturation cycles, gestational carrier cycles, oocyte recipient cycles, preimplantation genetic diagnosis cycles, and multiple pregnancies. The outcomes measured included anatomical, inflammation, vascular malperfusion, and villous maturation placental features. A multivariate analysis was conducted to adjust the results for factors potentially associated with placental pathology features. A total of 395 live births were included in the final analysis and were allocated to the study groups according to parity: primipara (n = 273) and multipara (n = 122). After adjustment for potential confounding factors, multiparity was found to be significantly associated with delayed villous maturation (OR 4.9; 95% CI 1.2-19.8) and primiparity was significantly associated with maternal vascular malperfusion (OR 0.6; 95% CI 0.3-0.8). We showed that parity has an impact on placental histopathological changes which in turn may affect perinatal outcome.