Severe maternal morbidities highly linked to pregnant woman's risk of death

The number of severe maternal morbidities (SMM) a pregnant woman has is highly linked to her risk of maternal death, according to a new study by researchers at ICES and St. Michael's Hospital.

SMM is defined by potentially life-threatening conditions such as ICU admission, invasive ventilation, and cardiac conditions that develop during pregnancy.

The study published today in JAMA Open Network looked at the data for more than 1.9 million hospital births in Ontario and found that the number of SMM conditions was strongly associated with maternal death up to 42 days postpartum. The researchers found that the number of SMM was exponentially associated with maternal death.

"Our findings show that some SMM are predictive of death, and in light of that we should be targeting preventable SMM, or limiting their progression using an early warning system, in order to reduce maternal deaths," says Dr. Joel Ray, lead author on the study and a researcher at ICES and the Li Ka Shing Knowledge Institute of St. Michael's Hospital.

The researchers found that women with one SMM were 20 times more likely to die than women who did not have an SMM and that risk grew to 102 times the risk with two SMM, and up to 2192 times higher the risk with six or more SMM.

The findings show the most common SMM conditions were postpartum hemorrhage with blood transfusion, ICU admission, puerperal sepsis (bacterial infection), severe preeclampsia (high blood pressure) and urgent need for hysterectomy.

The researchers identified 181 maternal deaths among all 1,953,943 births - a rate of 9.3 per 100,000 births. Of the 181 deaths, 68 per cent of the women who died had at least one SMM condition. Women who died tended to be older, first-time moms, of lower income and Afro-Caribbean origin, with a multi-fetal pregnancy, pre-existing diabetes, high blood pressure and kidney disease.

"Despite improved family planning and obstetric care, maternal deaths have remained stable in Canada, and as many as half of those are thought to be preventable. Our findings illustrate the value of utilizing existing maternal early warning systems and protocols to identify a woman's clinical deterioration in order to reduce maternal deaths," adds Ray.

"Prevalence of severe maternal morbidity and factors associated with maternal mortality in Ontario, Canada," was published today in JAMA Open Network.

Author block: Ray JG, Park AL, Dzakpasu S, Dayan N, Deb-Rinker P, Luo W, Joseph KS.

ICES is an independent, non-profit research institute that uses population-based health information to produce knowledge on a broad range of health care issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting health care needs of Ontarians, and a stimulus for discussion of practical solutions to optimize scarce resources. ICES knowledge is highly regarded in Canada and abroad, and is widely used by government, hospitals, planners, and practitioners to make decisions about care delivery and to develop policy.

St. Michael's Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 29 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital's recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

St. Michael's Hospital with Providence Healthcare and St. Joseph's Health Centre now operate under one corporate entity as of August 1, 2017. United, the three organizations serve patients, residents and clients across the full spectrum of care, spanning primary care, secondary community care, tertiary and quaternary care services to post-acute through rehabilitation, palliative care and long-term care, while investing in world-class research and education.