Making the Rare Matter: Why Canada Needs a System That Learns from Its Most Serious Pregnancy Complications

Health systems are designed to manage the expected. Protocols, procedures, and performance metrics revolve around what usually happens. But in pregnancy, it is the rare event – the unanticipated complication, the near-miss, the moment when systems fracture – that most often reveals whether care is truly working.
These are the moments when individuals are most vulnerable – and when health systems are most tested.
In Canada, one in every 57 pregnant women and people experiences a severe complication. Though statistically uncommon, these events are not random. They often result from a cascade of system-level factors – clinical, organisational, structural – that, with earlier insight, might have led to different outcomes. Women and people from Indigenous, Black, and other racialised and minoritised communities remain more than twice as likely to experience serious pregnancy-related complications as those from non-minoritised groups – an inequity that persists not because it is inexplicable, but because a system skilled at producing numbers has struggled to learn from them.
Numbers demand more than awareness. They require a system that reflects, responds, and reforms. And that begins with asking why.
The Canadian Obstetric Survey System (CanOSS) was created to respond to this gap. It is a national quality improvement initiative designed to study serious pregnancy complications not just as data, but as a window into system performance. CanOSS is not research. It is not a repository. It is a learning mechanism – a structured, confidential process for reviewing serious complications, understanding their causes, and turning insight into better care for all.
Its foundational premise is simple: begin where most research stops – by asking why.

Why this patient, in this setting, under these circumstances? Why did the system fail to prevent harm, and what must change to prevent it in future? These are not abstract questions. They are questions of design, coordination, and accountability. And in a field as complex and consequential as pregnancy health, they cannot be optional.
The CanOSS vision moved one step closer to reality on 12–14 May 2025, when more than 50 clinicians, researchers, health leaders, advocates, and community representatives from across Ontario convened in Hamilton for the CanOSS-Ontario Design Meeting. The energy in the room was unmistakable. Voices across disciplines, regions, and lived experiences came together not just to contribute, but to co-create. The discussions were rigorous and constructive – interrogating practical design questions, exploring ethical data stewardship, and shaping how findings will be returned to systems to drive change.
What emerged was more than a plan. It was momentum.
Momentum toward a provincial system that does not treat severe pregnancy complications as unpredictable anomalies, but as critical signals – each one an opportunity to understand how care performs under pressure, and how it must evolve. The meeting affirmed that the appetite for systemic learning exists. What is needed now is the infrastructure to make it possible across Canada.
That is what CanOSS aims to provide: a process that listens with intent, examines without compromise, and acts with purpose. A model that supports systems to reflect, learn, and improve. A mechanism that asks ‘why’ – so fewer lives are shaped by ‘what if’. And above all, a commitment to continually improve care.
As rates of serious pregnancy complications rise in Canada, the lack of resources, time, or infrastructure can no longer be used as an excuse. Every complication we prevent brings us closer to a future where no pregnancy is left to chance.
This is not just a public health imperative. It is our duty of care.