A recent study published in JAMA Network Open examines whether the use of hormonal contraception (HC) increases the risk of postpartum depression, a prevalent mental health issue that affects many new mothers.
Link Between Depression and Postpartum Period
Hormonal contraception has long been recognized as a potential risk factor for depression, but its effects on postpartum depression—a period that already elevates the risk of mental health disorders—remain unclear. Over the past two decades, the prescription of HC in the postpartum period has risen, with more women starting contraception soon after childbirth. Current estimates suggest that approximately 40% of mothers in Denmark begin using HC within the first year after delivery.
This shift prompts questions about whether starting HC during the postpartum period might further increase the already heightened risk of depression.
Study Methodology and Design
The study utilized data from Danish national registries, examining women who gave birth for the first time between January 1, 1997, and December 31, 2022. Crucially, none of the participants had a history of depression in the 24 months prior to childbirth. The analysis focused on four types of hormonal contraception: combined oral contraceptives (COCs), combined nonoral contraceptives (CNOCs), progestogen-only pills (POPs), and progestogen-only nonoral contraceptives (PNOCs).
The study cohort comprised 610,038 first-time mothers, with 41% initiating HC within 12 months postpartum. The average age of HC users was 27.6 years, compared to 29.6 years for non-users.
Increased Risk of Depression Among HC Users
The findings revealed that 24% of postpartum women prescribed HC used COCs, while smaller percentages used CNOCs, POPs, and PNOCs. Around 50% of the women began using contraception between seven and 10 weeks after childbirth.
In the first 12 months after delivery, 1.5% of the participants developed depression. The incidence of depression was significantly higher among women who used HC—21 cases per 1,000 person-years—compared to 14 cases per 1,000 person-years among non-users. This represents a 50% higher risk of postpartum depression for HC users compared to non-users.
The absolute risk of developing postpartum depression was found to be 36% higher for non-users than the baseline risk, and 54% higher for HC users, an 18% increase in absolute risk.
Risk Differences by Type of Contraception
When broken down by type of HC, the risk of postpartum depression was higher for women using combined oral contraceptives (COCs), which showed a 72% increased risk. The use of combined nonoral contraceptives, such as vaginal rings and patches, nearly doubled the risk, with a 97% increase in depression rates. Progestogen-only nonoral contraceptives (PNOCs), including implants, depot injections, and intrauterine systems, raised the risk by 40%.
Interestingly, progestogen-only pills (POPs) did not follow this pattern. Initially, POPs were associated with a lower depression risk, but after eight months postpartum, the risk began to rise.
Impact of Mental Health History and Timing of Contraception
The study also found that women with no history of mental illness were 63% more likely to develop postpartum depression compared to 32% of women with a history of mental health issues. Additionally, depression rates increased more among women who initiated HC early in the postpartum period, with the first seven months showing the highest risk for those who started contraception soon after childbirth.
Conclusions and Need for Further Research
The study highlights the early postpartum period as particularly vulnerable to depressive changes, driven by both hormonal fluctuations and psychological stressors. While all types of HC—except for POPs—were associated with an increased risk of postpartum depression, further research is necessary to confirm whether breastfeeding may influence this risk.
Women who breastfeed are often advised to use progestogen-only contraceptives, as combined hormonal contraceptives can affect lactation. The findings from this study warrant additional investigation to better understand the role of breastfeeding and potential selection bias in the relationship between HC use and postpartum depression.
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