Substance Use in Mothers: ED Visits Rise (CMAJ, USMLE Review)

Emergency department (ED) visits for substance use among mothers with dependent children in Ontario, Canada, rose by almost 5% a year between 2008 and 2024, according to a large study in the Canadian Medical Association Journal (CMAJ). Among females without children, the increase was about 2% a year. The growth was concentrated in mothers under 25, and the study is observational, so it describes a trend but does not explain its cause.

What happened

Researchers used ICES data from 2008 to 2024 on all females in Ontario who were giving birth and had at least one child age 18 or younger. They compared these birthing parents with other females who did not have children. The study included 988,106 birthing parents, matched by age to 1,198,063 other females.

The main findings:

• ED visits for substance use rose almost 5% a year in mothers with dependent children, compared with almost 2% a year in females without children.
• Mothers under 25 drove much of the increase. In this group, rates grew more than four times faster than in other females.
• Hospital admissions for substance use followed a similar pattern.
• Relative increases were largest for amphetamines, cannabis and opioids.
• Alcohol was still the biggest driver in absolute terms. It accounted for 46% of ED visits and 41% of hospitalizations for substance use in mothers in 2024.
• Overall frequency: ED visits and hospitalizations for substance use remain relatively rare in mothers, affecting around 0.5%.

Why it matters

Much of the public discussion of the opioid and toxic drug crises has focused on overdoses and deaths. This study looks at a broader signal: acute care use. The authors asked whether mothers had been spared these overlapping crises. In their words, "the answer appears to be no."

There is also a child-health angle. Growing up with a parent who has a substance use disorder is considered an adverse childhood experience (ACE). ACEs can raise a child's risk of poor health, developmental challenges and future substance use. The authors note there is surprisingly little evidence on substance use in parents compared with the general population. They suggest that an increasing number of children in Ontario may be growing up with a mother who has a serious substance use disorder.

The authors also point out that for every mother who reaches the ED or hospital, there are likely others who did not seek care, either because of stigma or because their use was not severe enough to need hospital care.

Their suggestions for the health system include integrated services that address both substance use and mental health, and programs that accommodate parenting responsibilities. They also name upstream measures: income and housing supports, and prevention of intimate partner violence.

What to know for the USMLE: substance use disorders

The news is epidemiology, but the exam tests the clinical pictures behind these ED visits. Here are the high-yield points.

• Opioid intoxication: the classic triad is miosis, respiratory depression and CNS depression. Treatment is naloxone, a short-acting competitive mu-receptor antagonist. Because its half-life is shorter than that of many opioids, re-sedation can occur.
• Opioid withdrawal: unpleasant but rarely life-threatening. Look for mydriasis, lacrimation, rhinorrhea, yawning, piloerection ("cold turkey"), myalgias, nausea, vomiting and diarrhea. Know the maintenance options: methadone (full agonist), buprenorphine (partial agonist) and naltrexone (antagonist). Clonidine helps with autonomic symptoms.
• Amphetamine intoxication: a sympathomimetic picture with euphoria, agitation, tachycardia, hypertension, mydriasis, decreased appetite, hyperthermia and sometimes psychosis. Severe cases can cause arrhythmias, seizures and rhabdomyolysis. Benzodiazepines are first-line for agitation and sympathomimetic toxicity.
• Amphetamine withdrawal: the "crash," with fatigue, hypersomnia, increased appetite, dysphoria or depression, and a risk of suicidality. Contrast this with cocaine, which blocks reuptake. Amphetamines mainly increase release of catecholamines.
• Cannabis: acts on CB1 receptors. Intoxication produces conjunctival injection, dry mouth, increased appetite, impaired short-term memory and altered time perception. Anxiety or paranoia can occur. Chronic heavy use is associated with cannabinoid hyperemesis syndrome, which classically improves with hot showers. Withdrawal is mild: irritability, insomnia and decreased appetite.
• Alcohol withdrawal: the timeline is a favorite on exams. Tremor and anxiety start within about 6–24 hours, alcoholic hallucinosis at about 12–48 hours, seizures at about 12–48 hours, and delirium tremens at about 48–96 hours. DTs involve autonomic instability and confusion, and carry real mortality. First-line treatment is benzodiazepines. Give thiamine before glucose to reduce the risk of Wernicke encephalopathy.
• Perinatal and pediatric links: maternal opioid use can cause neonatal abstinence syndrome (irritability, high-pitched cry, tremor, poor feeding, diarrhea). Maternal alcohol use causes fetal alcohol syndrome (microcephaly, smooth philtrum, thin upper lip, intellectual disability). Maternal opioid use disorder is a classic vignette that tests whether you know opioid agonist therapy (methadone or buprenorphine) is preferred over abrupt withdrawal in pregnancy.
• Screening and approach: know the CAGE questionnaire, the SBIRT framework (screening, brief intervention, referral to treatment), and the stages of change. In ethics and communication questions, a nonjudgmental, confidential approach is almost always the right answer. Stigma, which the authors cite as a barrier to seeking care, is a recurring theme.
• ACEs: know the term, and that ACEs are linked to later substance use, mental illness and chronic disease.

Limitations

• Observational design. The study shows rates rising over time. It cannot show why. The authors state explicitly that it does not examine whether motherhood or parenthood itself is causing the increase in substance use.
• Young mothers. The authors suggest the higher rates in mothers under 25 likely relate to other factors that lead to having children earlier in life and may also raise the risk of substance use. This is their interpretation, not a tested finding.
• Acute care only. The study measures ED visits and hospitalizations, not all substance use. The authors note that many mothers with substance problems never reach these settings. The true burden is therefore likely larger than what was captured.
• One province. The data come from Ontario, so the numbers may not translate directly to other regions or health systems, including the US.
• Rare outcomes. About 0.5% of mothers had an ED visit or hospitalization for substance use. The rises are real, but the absolute risk remains low.
• Alcohol interpretation. Alcohol's large share may reflect marketing aimed at women, as one author suggests with the "pinking" of alcohol. This is a comment from the investigators, not something the study tested.

FAQ

Did substance use rise more in mothers than in other women?

Yes, for ED visits. In this Ontario study, visits rose almost 5% a year in mothers with dependent children and almost 2% a year in females without children. Mothers under 25 saw rates grow more than four times faster than other females.

Which substance causes the most ED visits in mothers?

Alcohol. In 2024 it accounted for 46% of ED visits and 41% of hospitalizations for substance use in mothers. Opioids, amphetamines and cannabis had the largest relative increases over time, but alcohol remained the most common problem.

Does this study prove that being a mother raises substance use?

No. The design is observational, and the authors state that it does not examine whether motherhood or parenthood itself drives the trend. It shows that mothers were not spared from rising substance-related acute care use.

Key takeaways

• In Ontario from 2008 to 2024, substance-related ED visits rose almost 5% a year among mothers with dependent children versus almost 2% a year among females without children, with the fastest growth in mothers under 25.
• Alcohol remained the leading substance behind ED visits and hospitalizations, while opioids, amphetamines and cannabis grew fastest in relative terms. The study is observational and cannot show causes.
• For the USMLE, review the intoxication and withdrawal syndromes of opioids, amphetamines, cannabis and alcohol, and their perinatal consequences, including neonatal abstinence syndrome and fetal alcohol syndrome.