Le Ray C, et al. - Researchers performed a population-based cohort-nested case-control study to determine the association between IVF and severe maternal morbidity (SMM). Further, they examined the role of multiple pregnancy as an intermediate factor. Participants comprised 2540 women with SMM, according to the EPIMOMS definition, as cases and 3651 randomly selected women who gave birth without SMM as controls. In IVF pregnancies, they observed higher risk of SMM after adjustment for confounders. Women with IVF with oocyte donation exhibit higher risks, as per exploratory results, however with wide confident intervals, thus further confirmation is recommended. Multiple pregnancy seems to mediate a large part of the association between IVF with autologous oocytes and SMM.