Le Ray C, et al. - Researchers performed population-based cohort-nested case-control study to investigate how IVF is associated with severe maternal morbidity (SMM). Further, they explored the role of multiple pregnancy as an intermediate factor. According to the EPIMOMS definition, 2540 women with SMM comprised the cases; controls comprised 3651 randomly selected women who gave birth without SMM. Observations revealed a higher risk of SMM in IVF pregnancies after adjustment for confounders. As per exploratory results, higher risks were evident among women with IVF with oocyte donation, however with wide confidence intervals, thus needing to be confirmed. Multiple pregnancy seemed to mediate a large part of the association between IVF with autologous oocytes and SMM.