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Death risk up to 12 times higher for mothers with prenatal opioid use


Approximately one in 20 mothers whose babies are born with neonatal abstinence syndrome (NAS) died within 10 years of delivery in both England and Canada, according to a new study from researchers at ICES, The Hospital for Sick Children (SickKids) and UCL.

Neonatal abstinence syndrome (also called NAS) is a group of symptoms experienced by babies from withdrawal from certain drugs (predominantly opioids) that they are exposed to in the womb before birth. It is also a widely used measure of material use of opioids during pregnancy.

The study published today in PLOS Medicine, looked at data that included all hospital births in England and in Ontario, Canada from 2002 to 2012 and analyzed death rates through to 2016. The researchers examined data on 13,577 mothers in England and 4,966 in Ontario with infants with NAS and compared it to 4,205,675 mothers in England and 929,985 in Ontario whose infants did not have NAS.

The researchers found that at 10 years after giving birth, 5.1 per cent of English mothers with infants with NAS and 4.6 per cent of Ontarian mothers had died compared with 0.4 per cent of mothers whose infants did not have NAS in both countries. This translates to an 11 to 12 times higher risk of death associated with prenatal opioid use. The majority of deaths in mothers with infants with NAS were from avoidable causes such as intentional and unintentional injuries. 

Opioids are now a leading cause of death of young and middle-aged people in North America and rates of use and misuse are also increasing in the United Kingdom. There has been a steep increase in the number of women who use opioids during pregnancy, which can result in their infants having signs of NAS. Most studies of NAS focus on the child’s health, with very few about the mother’s health.

“Pregnancy care is an opportunity to identify mothers who may need addiction services and other support to improve their health and that of their families” says Dr. Astrid Guttmann, primary author on the study, chief science officer at ICES, staff paediatrician and senior associate scientist at SickKids and professor of paediatrics with a cross appointment in Health Policy, Management and Evaluation and the Epidemiology Division at the Dalla Lana School of Public Health at the University of Toronto. 

“We were struck by how consistent the findings were in both England and Canada. This is despite differences in the profile of opioid users in England and Canada suggesting both countries need to focus on improving long-term care for mothers with opioid addiction,” says Dr. Ruth Blackburn, co-primary author and UKRI innovation fellow at the UCL Institute of Health Informatics in London, England. 

The researchers also found that mothers with infants with versus without NAS were more likely to live in poverty, have other mental health and addiction disorders and have their infants placed in out of home care.

The researchers add that policymakers focused on harm reduction related to opioid use should include a focus on pregnant mothers and their children; public health programs such as nurse home visitors need to extend past the current period of only one to two years after birth.

UCL and the University of Toronto, including SickKids and other affiliated hospitals, are strategic global partners working together to address a range of global challenges. The partnership is built on more than 30 established collaboration in fields such as health sciences, city building and education, with new research collaborations being developed in areas with important implications, such as artificial intelligence and nanotechnology.

“Long-term mortality in mothers of infants with neonatal abstinence syndrome: a population-based parallel-cohort study in England and Ontario, Canada,” was published November 26, 2019 in PLOS Medicine.

Author block: Astrid Guttmann, Ruth Blackburn, Abby Amartey, Limei Zhou, Linda Wijlaars, Natasha Saunders, Katie Harron, Maria Chiu and Ruth Gilbert.

ICES is an independent, non-profit research institute that uses population-based health information to produce knowledge on a broad range of healthcare issues. Our unbiased evidence provides measures of health system performance, a clearer understanding of the shifting healthcare 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. In October 2018, the institute formerly known as the Institute for Clinical Evaluative Sciences formally adopted the initialism ICES as its official name. For the latest ICES news, follow us on Twitter: @ICESOntario

About The Hospital for Sick Children (SickKids)
The Hospital for Sick Children (SickKids) is recognized as one of the world’s foremost paediatric health-care institutions and is Canada’s leading centre dedicated to advancing children’s health through the integration of patient care, research and education. Founded in 1875 and affiliated with the University of Toronto, SickKids is one of Canada’s most research-intensive hospitals and has generated discoveries that have helped children globally. Its mission is to provide the best in complex and specialized family-centred care; pioneer scientific and clinical advancements; share expertise; foster an academic environment that nurtures health-care professionals; and champion an accessible, comprehensive and sustainable child health system. SickKids is a founding member of Kids Health Alliance, a network of partners working to create a high quality, consistent and coordinated approach to pediatric healthcare that is centred around children, youth and their families. SickKids is proud of its vision for Healthier Children. A Better World. For more information, please visit www.sickkids.ca. Follow us on Twitter (@SickKidsNews) and Instagram (@SickKidsToronto).

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Ruth Blackburn is supported by a UKRI Innovation Fellowship funded by the Medical Research Council (Grant No: MR/S003797/1) and both Ruth Blackburn and Ruth Gilbert benefit from the Health Data Research UK, an initiative funded by UK Research and Innovation, Department of Health and Social Care (England) and the devolved administrations, and leading medical research charities. This work also benefitted from the National Institute for Health Research (NIHR) Policy Research Programme and supported by the Administrative Data Research Centre for England by the Economic and Social Research Council, and infrastructure funded by the NIHR GOS BRC.


Deborah Creatura
Media Advisor, ICES
[email protected]
(o) 416-480-4780 or (c) 647-406-5996


Sasha Babakhanova
The Hospital for Sick Children (SickKids)
[email protected]   
416-813-7654 ext 228469

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