Longer Addiction Medication Use Tied to Lower Postpartum Overdose Risk

The more days a pregnant patient spends on medication for opioid use disorder around delivery and in the weeks that follow, the lower her risk of a later overdose or death, according to a study of 9,360 pregnancies published October 1 in JAMA Network Open.

Researchers at Vanderbilt University School of Medicine, working with collaborators at Emory University, tracked people enrolled in TennCare, Tennessee's Medicaid program, who had been dispensed buprenorphine or naltrexone at some point in the 132 days spanning 90 days before delivery through 41 days after. They then followed each pregnancy from postpartum day 42 through day 365 for a first nonfatal overdose or death.

Over that window, 148 of the 9,360 pregnancies produced a first outcome — 109 nonfatal overdoses and 39 deaths, or about 1.6 percent of the cohort. More medication days were associated with progressively lower risk, and a modeled 132-day supply was linked to roughly half the hazard of a first overdose or death compared with a single day of medication, after statistical adjustment.

The finding arrives in a corner of medicine where the stakes are unusually high: the authors note that overdose is the leading cause of maternal mortality in the United States.

What the study measured

The cohort was drawn from people aged 15 to 44 who delivered a live-born infant at 20 weeks of gestation or later between 2007 and 2020, with follow-up running through 2021. Records came from TennCare claims linked to birth and death certificates and to Tennessee hospital discharge data.

Everyone in the analysis had at least one day of medication dispensed during the exposure window and continuous TennCare enrollment around it, allowing gaps of no more than five days. Overlapping fills were deduplicated so that each calendar day counted once.

Nearly all of the treatment was buprenorphine. Of the 9,360 pregnancies, 9,085 — 97.1 percent — involved buprenorphine alone, 172 involved naltrexone alone, and 103 involved both. The median total supply during the window was 88 days: 62 days before delivery and 30 after.

Why the postpartum months matter

For most chronic conditions, continuity of care is unremarkable. For opioid use disorder, the period after birth has long been a recognized danger zone. Patients often lose contact with prescribers once obstetric care ends, and the shift in routine can interrupt medication for opioid use disorder at precisely the moment when tolerance has fallen and relapse risk is elevated.

The study's authors frame the postpartum year as a stretch in which staying on medication "may be particularly important," and the data show a dose-response pattern rather than a threshold: the hazard fell as cumulative days of supply rose, across the range the researchers could observe.

That pattern is consistent with earlier work linking buprenorphine continuity to lower mortality, but it extends the evidence into a population that is rarely studied in large numbers, and it does so with linked vital records rather than self-report.

What the findings do not prove

The study is observational, so it cannot establish that longer treatment itself caused the lower risk. People who fill more prescriptions may differ from those who fill fewer in ways the analysis could not fully capture — steadier housing, stronger engagement with care, better insurance coverage through pregnancy and beyond.

Pharmacy dispensing records show that medication was supplied, not that every dose was taken. And because 97 percent of the cohort received buprenorphine, the numerical results primarily describe buprenorphine-treated pregnancies in one state's Medicaid program. Naltrexone appears too rarely here to support conclusions of its own.

The authors also caution against reading 132 days as a clinical target. That figure was simply the maximum possible coverage inside the study window, and the comparison was relative, not a claim that any individual patient's absolute risk would drop by 48 percent.

What it means for care

Tennessee's experience is unlikely to be unique. Medicaid finances a large share of births among people with opioid use disorder nationwide, and federal rules have been loosened in recent years to let more clinicians prescribe buprenorphine without special certification. What the new data suggest is that the prescribing decision is only half the equation. Retention — keeping the prescription filled through delivery and well past the six-week postpartum visit — is where the mortality signal appears.

Whether that translates into policy is another question. Continuous Medicaid coverage after birth varies by state, and the study period predates several federal changes to postpartum eligibility. The researchers say the next step is understanding which supports actually keep patients in treatment, rather than simply proving again that they should be.