Favilli A, Tosto V, Ceccobelli M, et al. - Researchers sought to analyze all known risk factors related to retained placenta, which represents a cause of maternal morbidity and mortality in 0.5%–3% of all vaginal deliveries. They identified 35 studies meeting the inclusion criteria via performing a systematic literature review. The most recurrent, independent risk factors for retained placenta comprised maternal age, previous cesarean sections, previous dilation and curettage, previous retained placenta, labor induction. Fascinating new proposal risk factors are previous estro-progestins therapy, morphological placental features (weight, shape, insertion of umbilical cord, implantation site), endometriosis, Assisted Reproductive Technologies, Apgar score. No firm conclusions could be drawn because of the lack of robustness of old and new data.