Could birth control raise depression risk in new mothers?

Copenhagen University Hospital–Rigshospitalet and collaborating Danish universities have conducted statistical research suggesting that starting hormonal contraceptive (HC) use postpartum is associated with a 49% higher risk of developing depression compared to nonusers, though the modeled absolute risk difference over 12 months was only 0.18 percentage points. Associated risks were assessed to be higher the earlier use was initiated postpartum.

HC use has previously been connected to elevated depression risk in the general population, particularly among adolescents and younger women. How this impacts a postpartum context has remained uncertain.

Postpartum itself is linked to heightened vulnerability to mental health disorders, including depression. Women are commonly offered HCs for contraception during this time, yet studies on the intersection of postpartum and HC are lacking.

In Denmark, as many as 40% of mothers initiate HC methods within the first year after delivery and throughout the past 20 years they have started at a shorter and shorter time interval after delivery.

In the study, "Postpartum Hormonal Contraceptive Use and Risk of Depression," published in JAMA Network Open, researchers conducted a population-based cohort study based on nationwide Danish health data to examine how postpartum HC use is associated with depression compared with no HC exposure.

Researchers analyzed data between 1997 and 2022 on more than 610,000 first-time mothers; 248,274 (40.7%) initiated HCs within 12 months postpartum. Data were linked using personal identification numbers assigned to all Danish residents. Hormonal contraceptives were categorized as combined oral contraceptives, combined non-oral contraceptives, progestogen-only pills, and progestogen-only non-oral contraceptives.

Use of combined oral contraceptives was initiated by 143,751 women (23.6%), combined non-oral contraceptives by 5,465 (0.9%), progestogen-only pills by 66,612 (10.9%), and progestogen-only, non-oral contraceptives by 32,446 (5.3%). A subgroup of 29,864 women (4.9%) used levonorgestrel-releasing intrauterine systems.

Mean exposure time for HC users was 7.7 months overall; 7.0 months for combined oral contraceptives, 7.4 months for combined non-oral contraceptives, 8.8 months for progestogen-only pills, and 8.0 months for progestogen-only non-oral contraceptives.

Depression developed in 9,251 women (1.5%) within 12 months after delivery. Crude incidence rate was 21 per 1,000 person-years among HC users and 14 per 1,000 person-years among non-users.

Modeling estimated postpartum depression risk under different contraceptive-use scenarios showed variation across HC types. HC use (combined) was associated with a 49% higher instantaneous risk of depression compared with nonuse (adjusted hazard ratio [AHR], 1.49; 95% CI, 1.42–1.56).

In a hypothetical scenario where no women had initiated hormonal contraception, the 12-month average absolute risk of depression was estimated at 1.36% (95% CI, 1.32%–1.39%).

Among women recorded as initiating hormonal contraception (based on prescription fill dates), the estimated average risk was 1.54% (95% CI, 1.50%–1.57%), resulting in an absolute risk difference of just 0.18 percentage points (95% CI, 0.16%–0.20%).

Exploratory analysis examined whether earlier initiation of combined oral contraceptives was associated with greater depression risk. Rate of depression was higher among women who began use earlier in the postpartum period and declined steadily over the first seven months, while remaining elevated throughout the 12-month period compared with nonusers.

Likelihood-ratio tests supported a negative linear association between time to initiation and depression rate, with a rate ratio of 0.61 (95% CI, 0.48–0.79) per year after delivery.

Start of HC after childbirth was associated with an increased risk of developing depression within the first 12 months postpartum. Risk was elevated across all HC types except progestogen-only pills, which showed a time-varying pattern with reduced early risk and increased risk later in the study.

No consistent age-related trend in depression risk was found after accounting for time-varying covariates. Risk was greater among women with no history of mental disorder compared with those who had a prior diagnosis. Findings raise the possibility that routine postpartum HC initiation may contribute to elevated rates of depression in this period.

As an observational study, these findings do not establish causation. Authors noted that prior studies outside the postpartum period have reported stronger associations between HC use and depression among younger women.

No direct comparison was made to non-postpartum populations initiating hormonal contraception, and no demographically adjusted comparison to baseline depression rates outside the postpartum context was included for comparison.

Another aspect that could influence the correlation (perhaps for future study) are nurse and midwife protocols for patients exhibiting symptoms of postpartum stress, anxiety, sleeplessness, excessive bleeding or depression.

Denmark has robust postpartum follow-up care, with regular patient in-home visits by trained professionals. Trends seen in the data could easily be reflective of routine patient care practices.

More information: Søren Vinther Larsen et al, Postpartum Hormonal Contraceptive Use and Risk of Depression, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.2474

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This article was originally published on MedicalXpress Breaking News-and-Events.