Le Ray C, et al. - Researchers performed a population-based cohort-nested case-control study examining the association between in vitro fertilization IVF and severe maternal morbidity (SMM). Further, they investigated the role of multiple pregnancy as an intermediate factor. This study included cases comprising 2540 women with SMM according to the EPIMOMS definition and controls comprising 3651 randomly selected women who gave birth without SMM. Women with IVF were noted to be at significantly higher risk of SMM. Women with IVF with autologous oocytes (IVF-AO) had a significantly higher risk of SMM, for all-cause SMM, for near misses, and for intra/postpartum hemorrhages. Women with IVF with oocyte donation (IVF-OD) were at significantly higher risk of SMM, for all-cause SMM, for near misses, for SMM due to hypertensive disorders and due to intra/postpartum hemorrhages. As per path-analysis, multiple pregnancy seemed to mediate 21.6% of the risk associated with IVF-OD and 49.6% of the SMM risk associated with IVF-AO.