In Canada, it's thought those serious (maternal) cases happen at a rate of less than 18 out of every 1,000 deliveries. But that estimate is based specifically on labour and delivery, the relatively short period of time spanning from the onset of regular contractions to the moment the placenta is expelled after childbirth.

New Canadian research suggests close to a third of life-threatening complications also happen to women after that period, during the early weeks following the delivery — a time when mothers typically experience far less medical tracking and support than they did during pregnancy.

From sepsis to severe hemorrhage, nearly 30 per cent of cases of severe maternal morbidity happened within the first six weeks postpartum, according to findings based on a cohort of more than a million births in Ontario between 2012 and 2021.

More than half of those serious cases were during labour and delivery itself, while another 16 per cent occurred earlier during pregnancy.