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CanOSS Ontario

Establishing a Provincial Model for Severe Maternal Morbidity (SMM) Surveillance

Severe maternal morbidity (SMM) refers to serious complications during pregnancy, childbirth, or the postpartum period that result in severe illness, extended hospitalization, long-term disability, or increased risk of death. SMM rates are rising in Canada and are closely tied to maternal mortality. Leading causes include severe pre-eclampsia, HELLP syndrome, and severe postpartum hemorrhage.

In high-income countries, SMM has become a key quality indicator for maternal and reproductive health care. In response, many have implemented nationwide Obstetric Surveillance Systems (OSS) to identify the underlying causes of SMM and guide system-wide improvements in care. Canada currently lacks such a system.

 

Why Canada Needs a New Approach

While existing maternal health databases in Canada collect some clinical and demographic information, they often fail to capture contextual and systemic factors – such as how care is delivered, or disparities affecting Indigenous, Black, racialized, 2SLGBTQA+, and gender-diverse populations. Without this depth of insight, it’s impossible to make meaningful, targeted improvements in care quality or outcomes.

 

The CanOSS Model

The Canadian Obstetric Survey System (CanOSS) is being developed to fill this gap. Designed in collaboration with clinicians, researchers, community members, and individuals with lived experience, CanOSS will gather and analyze data on the modifiable and systemic contributors to SMM. A national Knowledge Hub has been created to support this work, including tools for education, implementation, and knowledge mobilization.

Image by Ian Schneider

Key findings

Given the complexities of Canada’s decentralized healthcare system and the diversity in infrastructure across provinces and territories, CanOSS will begin with a pilot in Ontario – home to 38% of the national population. This pilot phase, known as CanOSS Ontario, will function as a quality improvement initiative, modeled on public health program principles.

 

Informed by early feasibility studies and shaped by feedback from Ontario-based clinicians and reviewers of SMM cases, CanOSS Ontario will:

 

  • Adapt existing case review systems into a unified, systematic framework

  • Identify modifiable factors contributing to SMM

  • Implement evidence-based changes in care practices

  • Ensure findings are translated into actionable system-level improvements

 

All data collected will be fully de-identified and securely stored at McMaster University.

This pilot will lay the groundwork for a national obstetric surveillance system capable of improving maternal health outcomes across Canada.

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  2. Ukah UV, Platt RW, Auger N, Lisonkova S, Ray JG, Malhamé I, et al. Risk of recurrent severe maternal morbidity: a population-based study. Am J Obstet Gynecol. 2023 Nov;229(5):545.e1-545.e11. https://pubmed.ncbi.nlm.nih.gov/37301530/

  3. Dzakpasu S, Deb-Rinker P, Arbour L, Darling EK, Kramer MS, Liu S, et al. Severe Maternal Morbidity in Canada: Temporal Trends and Regional Variations, 2003-2016. J Obstet Gynaecol Can. 2019 Nov;41(11):1589-1598.e16. https://pubmed.ncbi.nlm.nih.gov/31060985/

  4. Government of Canada. Statistics Canada. 2023. Fertlity indicators. Available from: https://www150.statcan.gc.ca/n1/pub/71-607-x/71-607-x2022003-eng.htm

  5. Ray JG, Park AL, Dzakpasu S, Dayan N, Deb-Rinker P, Luo W, et al. Prevalence of Severe Maternal Morbidity and Factors Associated With Maternal Mortality in Ontario, Canada. JAMA Netw Open. 2018 Nov 9;1(7):e184571. https://pubmed.ncbi.nlm.nih.gov/30646359/

  6. Geller SE, Koch AR, Garland CE, MacDonald EJ, Storey F, Lawton B. A global view of severe maternal morbidity: moving beyond maternal mortality. Reprod Health. 2018 Jun;15(S1):98. https://pubmed.ncbi.nlm.nih.gov/29945657/

  7. World Health Organization, UNICEF, UNFPA, World Bank, UNDESA/Population Division. Trends in maternal mortality 2000 to 2020 [Internet]. 2023. Available from: https://iris.who.int/bitstream/handle/10665/366225/9789240068759-eng.pdf?sequence=1

  8. Knight M, Lewis G, Acosta C, Kurinczuk J. Maternal near-miss case reviews: the UK approach. BJOG Int J Obstet Gynaecol. 2014;121(s4):112–6. https://doi.org/10.1016/j.bpobgyn.2013.03.002

  9. Nair M, Choudhury MK, Choudhury SS, Kakoty SD, Sarma UC, Webster P, et al. IndOSS-Assam: investigating the feasibility of introducing a simple maternal morbidity surveillance and research system in Assam, India. BMJ Glob Health. 2016 Apr;1(1):e000024. https://pubmed.ncbi.nlm.nih.gov/28588919/

  10. Schaap TP, van den Akker T, Zwart JJ, van Roosmalen J, Bloemenkamp KWM. A national surveillance approach to monitor incidence of eclampsia: The Netherlands Obstetric Surveillance System. Acta Obstet Gynecol Scand. 2019;98(3):342–50. https://pubmed.ncbi.nlm.nih.gov/30346039/

  11. Donati S, Buoncristiano M, Lega I, D’Aloja P, Maraschini A, Group for the I working. The Italian Obstetric Surveillance System: Implementation of a bundle of population-based initiatives to reduce haemorrhagic maternal deaths. PLOS ONE. 2021 Apr 23;16(4):e0250373. https://www.iss.it/documents/20126/45616/ANN_19_04_10.pdf

  12. Tura AK, Girma S, Dessie Y, Bekele D, Stekelenburg J, Van Den Akker T, et al. Establishing the Ethiopian Obstetric Surveillance System for Monitoring Maternal Outcomes in Eastern Ethiopia: A Pilot Study. Glob Health Sci Pract. 2023 Apr 28;11(2):e2200281. https://pubmed.ncbi.nlm.nih.gov/37116928/

  13. Qian J, Wolfson C, Neale D, Johnston CT, Atlas R, Sheffield JS, et al. Evaluating a pilot, facility-based severe maternal morbidity surveillance and review program in Maryland—an American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine Rx at workT. Am J Obstet Gynecol MFM. 2023;5(4):1–4. https://pubmed.ncbi.nlm.nih.gov/36764455/

  14. Barrett J, D’Souza R. Launching the Canadian Obstetric Survey System – a pilot study. Hamilton Academic Health Sciences Organization (HAHSO) competition. Award period: 2 years. Award amount: $196,092.; 2023. Available from: https://ifpoc.org/project/launching-the-canadian-obstetric-survey-system-a-pilot-study/

  15. D’Souza R, Malhamé I. Improving Maternity Outcomes by Engaging Stakeholders in a Holistic Assessment of the Social and Clinical Determinants of Severe Maternal Morbidity in Canada – a Feasibility Study. CIHR Project Grant Competition. Award period: 3 years. Amount awarded $321,300. CIHR grant #462756.; 2021. Available from: https://webapps.cihr-irsc.gc.ca/decisions/p/project_details.html?applId=444788&lang=en

  16. D’Souza R, Seymour RJ, Knight M, Dzakpasu S, Joseph KS, Thorne S, et al. Feasibility of establishing a Canadian Obstetric Survey System (CanOSS) for severe maternal morbidity: a study protocol. BMJ Open. 2022 Mar 23;12(3):e061093. https://pubmed.ncbi.nlm.nih.gov/35321901/

  17. Malhamé I, D’Souza R. Canadian Perinatal Programs Coalition. Co-creating knowledge mobilization activities to address pregnancy-related near-miss events and deaths in Canada. National Women’s Health Research Initiative: Pan-Canadian Women’s Health Coalition Hubs Competition. Award period: 4 years. Amount awarded: $439,106. CIHR grant #494770.; 2023. Available from: https://webapps.cihr-irsc.gc.ca/decisions/p/project_details.html?applId=476802&lang=en

  18. CIHR Team on Improved Perinatal Health care Regionalization. Summary of Tiers of Obstetric and Neonatal Services in Canadian Hospitals. Vancouver; 2020. https://med-fom-phsr-obgyn.sites.olt.ubc.ca/files/2021/03/TOSDetailedJune2020.pdf

  19. Government of Canada SC. Population estimates, quarterly [Internet]. 2024 [cited 2024 Sep 11]. Available from: https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=1710000901

References

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