Prenatal Opioid Use Linked to Increased Mortality for Moms

Liam Davenport

November 28, 2019

Women with prenatal opioid use are over 10 times more likely to die during the 10 years after giving birth than women who do not use opioids, a study has found. Most of those deaths are avoidable, the researchers say.

Astrid Guttmann, MD, professor of pediatrics at the Dalla Lana School of Public Health at the University of Toronto, Ontario, Canada, and colleagues, studied data on more than 4 million mothers in England and almost 1 million in Ontario.

Using neonatal abstinence syndrome (NAS) as a marker for opioid use during pregnancy, they showed that mothers of infants with NAS were between 11 and 12 times more likely to die than other women for as long as 10 years after giving birth.

The findings were published online November 26 in PLoS Medicine.

The findings "provide a stark reminder of the vulnerability and sustained poor outcomes of these mothers," the authors write. "Policy responses to the current opioid epidemic will require effective strategies for risk mitigation and ongoing support for families affected by opioid use."

They also call for "large-scale linkage of health and social care administrative data," which would "facilitate ongoing research, program evaluation, and surveillance."

Coprimary author Ruth Blackburn, PhD, UKRI Innovation Fellow at the UCL Institute of Health Informatics in London, UK, said in a news release that they 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," she said.

Guttmann added that "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."

It is well-known that opioid addiction is associated with premature mortality in young and middle-aged adults.

Whereas the United States and Canada have the highest per capita prescription opioid consumption among Western nations, the authors note that prescription opioid use in England has increased, albeit without a similar increase in mortality rates.

These trends have been accompanied by increasing opioid use among pregnant women. Little, however, is known about associated mortality in women outside the perinatal period.

The team conducted a population-based cohort study of mothers aged 12 to 49 years and their live-born singleton infants delivered between April 2002 and December 2012.

For the English cohort, inpatient admission data were obtained from the National Health Service and linked to mortality data from the Office for National Statistics.

In Ontario, the team mined the Canadian Institute for Health Information Discharge Abstract Database and Ontario Mental Health Reporting System for hospital discharge records, which were then linked to various datasets to obtain cause of death information.

In Ontario, the study was supported by the Institute for Clinical Evaluative Sciences. In England, the study was funded by the National Institute for Health Research Policy Research Programme.

During the study period, 13,577 mothers in England had infants with NAS and 4,205,675 were control mothers. In Ontario, 4966 mothers had infants with NAS and 929,985 were control mothers.

Mothers of infants with NAS in both cohorts were significantly more likely than control mothers to live in neighborhoods in the lowest income quintile in both England and Ontario (P < .001, both regions), and more likely to have their infant discharge to care by social services (P < .001, both regions).

They were also younger on average than control mothers and, in Ontario, were significantly more likely to be teenage mothers (9.8% vs 3.7%; P < .001).

Higher comorbidity scores were also significantly more common among mothers of infants with NAS than control mothers (P < .001, both regions), and a significantly greater proportion had a previous psychiatric hospitalization (P < .001, both regions).

The mean duration of follow-up for mothers of infants with NAS and control mothers in England was 8.4 and 8.2 years, respectively, whereas the equivalent figures in Ontario were 7.2 and 8.6 years, respectively.

The crude cumulative mortality incidence was significantly higher for mothers of infants with NAS than control mothers in both cohorts.

In England, 5- and 10-year mortality rates were 1.81% and 5.13%, respectively, for mothers of NAS infants, compared with 0.15% and 0.42%, respectively, for control mothers (P < .001).

Similarly, 5- and 10-year mortality rates in Ontario were 1.85% and 4.58%, respectively, for mothers of infants with NAS, compared with 0.15% and 0.40%, respectively, for control mothers (P < .001).

The crude hazard ratio for all-cause mortality for mothers of infants with NAS versus controls was 12.1 in England and 11.4 in Ontario (P < .001 for both regions).

Most deaths among mothers of infants with NAS were deemed to be avoidable, accounting for more than 85% of deaths in England and 75% in Ontario, at a 10-year cumulative incidence of 42.9 and 30.8 deaths per 1000 population, respectively.

The most common causes of avoidable deaths were intentional and unintentional injuries, such as transport-related injuries and falls.

The study "has implications for research, practice, and policy to improve maternal and, arguably, child outcomes related to prenatal opioid use," the researchers explain.

They note that "enhanced treatment programs" integrating maintenance therapy, psychotherapy, reproductive health, and obstetric care have been effective in reducing substance misuse, unplanned pregnancies, and perinatal obstetric complications.

"Some evaluations of programs supporting mothers with opioid use and their children suggest that multifaceted services addressing health, addiction, housing, and parenting needs can improve parenting capacity and attachment and reduce child apprehension," the investigators add.

The team underlines that any interventions will "need to extend past the early postpartum period and include mothers whose children may not return home," and emphasize that the focus should not be only deaths from opioid overdose, as that "will miss the full extent of the problem."

PLoS Med. Published online November 26, 2019. Full text

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