Risk factors for third stage placental complications among primigravid women

Introduction: Third stage placental complications (TSPC) including partially or complete retained placenta, are a common obstetric complication. Previous studies have underlined risk factors for TSPC in heterogenous populations of women, whereas data regarding primigravid term women are scarce. We aimed to identify the factors associated with TSPC in this subset of parturients. Methods: A retrospective cohort study including all primigravid women who delivered vaginally a term, live-singleton neonate between 2011 and 2019. Women who underwent revision of the uterine cavity due to TSPC were compared with those who did not. Univariate and multivariate regression analyses were performed in order to identify the risk factors for TSPC. Results: Overall, 16,867 deliveries met the study inclusion criteria. Of those, 1097 (6.5%) deliveries were complicated by TSPC. Women with TSPC were older (p < 0.001) and with a higher proportion of lateral and fundal placental location (p < 0.001). In a multivariate regression analysis, the following factors were positively independently associated with TSPC: maternal age (aOR [95% CI] 1.26 (1.17-1.36), p < 0.001), the use of assisted reproduction technologies (aOR [95% CI] 1.26 (1.06-1.49), p = 0.007), preeclampsia (aOR [95% CI] 3.39 (1.89-6.10), p < 0.001), thrombocytopenia (aOR [95% CI] 1.83 (1.34-2.48), p < 0.001), oxytocin administration (aOR [95% CI] 1.29 (1.12-1.48), p < 0.001) and longer second stage duration (aOR [95% CI] 1.03 (1.003-1.05), p = 0.02). Fetal male gender was negatively associated with TSPC (aOR [95% CI] 0.80 (0.70-0.92), p = 0.002). Discussion: We have identified multiple independent risk factors for TSPC among primigravid women. This information can aid in patient counseling and delivery management in these subset of parturients.