Hydatidiform Mole with Coexisting Normal Pregnancy: A Systematic Review and Individual Participant Data Meta-Analysis

Background and Objectives: This study aimed to evaluate obstetric, neonatal, and oncologic outcomes of pregnancies complicated by a hydatidiform mole coexisting with a live fetus (HMCF) carried beyond viability, and to assess the impact of delivery mode on outcomes. Materials and Methods: A systematic review and individual participant data meta-analysis included HMCF cases progressing beyond 23 weeks. Obstetric and neonatal outcomes, delivery patterns, and oncologic risks were analyzed. Results: Among 118 pregnancies complicated by HMFC (124 newborns), most were complete moles (87%). Median delivery occurred at 31.6 weeks, with over half before 32 weeks. Common complications included vaginal bleeding (59%), preeclampsia (30%), and hyperthyroidism (18%). Cesarean delivery was performed in 79% of cases, often for mole-related factors, but was not associated with reduced maternal or oncologic risk. Neonatal deaths occurred exclusively in infants delivered ≤32 weeks, highlighting extreme prematurity as the key determinant of survival. Severe preeclampsia was strongly linked to earlier delivery. Conclusions: With close monitoring, continuation of HMCF pregnancies is possible. Neonatal mortality is mainly driven by prematurity, which appears to be an indirect consequence of HMFC through the development of mola-associated complications. Cesarean section does not appear to improve maternal and oncologic outcomes. Vaginal delivery can be considered when no standard contraindications exist.