The association of placental histopathological lesions and adverse obstetric outcomes in patients with Müllerian anomalies

Introduction: An increased risk of an unfavorable obstetric outcome has been reported in relation with Müllerian anomalies (MA). We evaluated whether placental lesions are more frequent among patients with MA and correlates with adverse pregnancy outcomes. Methods: The medical records and placental histopathologyy of consecutive patients with MA between 2007 and 2020 were reviewed. A control group matched for maternal age and pregnancy complications was selected in a 1:1 ratio. Characteristics were then compared between the MA and control groups. Results: The study group included 110 patients with MA. Patients in the MA group gave birth at earlier gestational age as (35.8 ± 3.3 vs 39.1 ± 1.3 weeks, respectively, P < 0.001). Placental weight <10th percentile was significantly more frequent in the MA cohort compared with controls (31% vs. 6%, respectively, p < 0.001). Higher rates of vascular and villous lesions of maternal vascular malperfusion (MVM) were also detected in the MA group (P = 0.04, P = 0.01, respectively). On multivariable analysis the presence of MA was an independent predictor of composite placental MVM lesions (OR 3.9, 95% CI 2.2, 6, p = 0.04). Using multivariate logistic regression models, the presence of MA was also found to be an independent predictor of small for gestational age (SGA), (OR 4.2, 95% CI 2.7, 11.7, p = 0.01). Discussion: MA are associated with placental MVM lesions and SGA independent of background confounders including gestational age – suggesting a placental involvement in the association between MA and adverse pregnancy outcomes. Prospective studies among larger cohorts are needed to corroborate our results.