A major study led by Hamilton researchers shows that serious, potentially life-threatening complications in pregnancy and postpartum are far more common in Canada than current monitoring captures — and nearly half occur before labour begins or after a baby is born.
The findings, published in CMAJ on March 16, 2026, point to a critical blind spot in how maternal health is tracked and raise urgent questions about whether the health-care system is catching warning signs early enough. The research was a collaborative effort between McMaster University, Hamilton Health Sciences, and St. Joseph’s Healthcare Hamilton.
“The events we examined are those that threaten a person’s life or long-term health, and almost half aren’t currently accounted for in Canada’s standard monitoring systems. That means we may be underestimating both the scale and timing of serious maternal risk,” says Giulia Muraca, senior author of the study and an associate professor with McMaster’s departments of Obstetrics and Gynecology and Health Research Methods, Evidence, and Impact.
The study used linked administrative and clinical registry data from ICES, an independent, not-for-profit research and analytics institute, and examined more than one million pregnancies between 2012 and 2021.
Researchers found that nearly 30,000 pregnancies involved severe maternal morbidity — complications such as major hemorrhage, sepsis, or acute organ dysfunction. While national surveillance typically focuses only on complications that occur during labour and delivery, the research team showed that 45 per cent of these dangerous events take place outside the delivery room, during pregnancy or in the six weeks postpartum.
The study also revealed that the types of complications — and the people most at risk — vary significantly depending on when they occur.
During pregnancy, acute abdominal emergencies, like acute appendicitis, were the most common serious issue. During labour, severe hemorrhage dominated. After birth, sepsis was the leading cause of severe illness.
Risk factors also shifted across stages: while complications during labour and postpartum showed a U-shaped pattern with age, complications during the period of pregnancy between conception and the onset of labour were especially common among birthing parents aged 15 to 24.
Taken together, the findings underscore the need for a broader, more comprehensive approach to maternal health surveillance in Canada — one that follows pregnant people from conception through the postpartum period. The researchers say the study offers a roadmap for policymakers looking to strengthen maternal health care and ensure that early warning signs aren’t missed.
“Severe maternal complications aren’t just a birthing-room issue — they occur across pregnancy and after birth, and many first appear in emergency departments, walk-in clinics and family physician offices, rather than obstetric and midwifery units. Improving maternal safety requires a whole-system approach, involving emergency care, primary care, maternity care teams and postpartum care teams,” says Rohan D’Souza, a co-author of the study and an associate professor in the departments of Obstetrics and Gynecology and Health Research Methods, Evidence and Impact at McMaster.
“This is about expanding our lens. We now have evidence that severe complications aren’t concentrated in labour alone – they’re happening throughout pregnancy and after birth. Better monitoring and earlier intervention could save lives,” adds D’Souza, who is also a maternal-fetal medicine physician at Hamilton Health Sciences and holds a Canada Research Chair in Maternal Health.
“These findings should sound the alarm for health-care providers and policymakers across the country,” said Benicio Frey, academic head of Mood Disorders and Women’s Mental Health and director of the Centre for Clinical Neurosciences at St. Joseph’s Healthcare Hamilton and one of the study’s authors.
“We need to improve how we monitor and track these severe health events well before and after the period around child delivery in order to save more lives.”
The study is part of the SERENE Project, a three-year research effort in partnership with a lived experience advisory network that is committed to exploring why and when severe maternal morbidity happens, which people are most affected, what are the long-term physical, social and mental health implications, and how severe maternal morbidity and its negative effects can be reduced.
Funding for this study was provided by the Juravinski Research Institute, a partnership with Hamilton Health Sciences, McMaster University and St. Joseph’s Healthcare Hamilton established through the generosity of the late Margaret and Charles Juravinski, as part of the SERENE Project.