IntroductionPregnant polycystic ovary syndrome (PCOS) patients are at increased risk for myriad obstetric complications, with the placenta thought to play a key role in their development. We aimed to evaluate placental histopathology patterns in placentas of women with PCOS who underwent in-vitro-fertilization (IVF). MethodsThis retrospective study utilized full gross and histopathologic assessment of placentas of all women who had IVF treatment and delivered at the Royal Victoria Hospital from 2009 to 2017, regardless of complications or mode of delivery. Pathologic findings included anatomic, inflammation, villous maturation, and vascular mal-perfusion features. Placentas of PCOS women were compared to those of ovulatory controls. Multivariate logistic regression was used to adjust results for confounding factors potentially associated with significant placental and perinatal characteristics. ResultsWomen with PCOS (n = 47) were more likely to develop gestational diabetes mellitus compared to ovulatory controls (n = 1121) (38.3% vs. 9.8%, p < 0.001). Placentas from PCOS women were more likely circumvallate placentas (aOR 8.3, 95%CI 1.9–37.3) and more likely to have a hypercoiled umbilical cord (aOR 6.8 95%CI 1.3–36.8) and villitis of unknown etiology (aOR 6.1, 95%CI 1.5–25.6). There was an increased likelihood of chorangiosis (aOR 2.7, 95% CI 1.3–5.8), evidence of fetal vascular malperfusion based on one criteria (aOR 2.7, 95%CI 1.1–7.4), or more than one criteria (aOR 6.4, 95%CI 1.6–25.9), more nucleated fetal red blood cells (aOR 5.2, 95%CI 1.1–24.5), and a higher likelihood of chorangiomas (aOR 9.4, 95%CI 1.6–55.1) in placentas from PCOS women than in controls. DiscussionIVF pregnancies’ placental histopathological characteristics are significantly impacted by an underlying diagnosis of PCOS, including important anatomic changes and vascular placental abnormalities.