A recent decade-long observational study conducted in Ireland found an association between breastfeeding and a lower likelihood of mothers experiencing anxiety and depression over a 10-year follow-up period.
Background
Breastfeeding is known to offer benefits for infant and maternal physical health, including reduced infection rates in infants and lower risks of cardiovascular disease, cancer, and diabetes in mothers. Evidence also connects breastfeeding to improved infant mental health and cognitive development. For maternal mental well-being, the link between breastfeeding and decreased postnatal depression is established, with stronger effects observed for exclusive breastfeeding. Biological mechanisms potentially involved include lactation hormones such as oxytocin, which supports bonding and stress regulation.
Study Design
Researchers utilized data from a cohort initially recruited from a Dublin maternity hospital during the women's second pregnancy. The analysis included 168 multiparous women with complete lifetime breastfeeding and mental health data at the 10-year postpartum follow-up. Women who were pregnant or breastfeeding at the time of the 10-year assessment were excluded.
Breastfeeding exposure was assessed using validated questionnaires at 10 years, covering aspects such as ever breastfeeding, duration of any breastfeeding, duration of exclusive breastfeeding, and cumulative breastfeeding duration of at least 12 months. Mental health outcomes were based on self-reported diagnoses of depression or anxiety or reported antidepressant medication use. Potential confounders, including age, education, socioeconomic status, and baseline well-being, were considered. Logistic regression modeling was used for analysis, adjusting for baseline age, baseline well-being, physical activity, and alcohol intake.
Key Findings
At the 10-year follow-up, participants averaged 42.4 years old, with most being premenopausal. Nearly three-quarters (72.6%) of participants reported having breastfed. The median duration of exclusive breastfeeding was 5.5 weeks, and any breastfeeding was 30.5 weeks. Over one-third of the women had breastfed for at least 12 months across their lifetime.
Depression or anxiety was reported by 13.1% of women at the 10-year follow-up and by 20.8% at one or more points during the study period. Women reporting depression or anxiety were observed to be younger, have lower baseline well-being scores, and a higher probability of smoking. They also reported being less likely to have breastfed and had shorter durations of both exclusive and total breastfeeding.
After adjusting for baseline differences and alcohol intake, having breastfed at any point was associated with lower odds of anxiety and depression at the 10-year follow-up. When considering depression or anxiety across the entire study period, having breastfed, longer exclusive breastfeeding, and cumulative breastfeeding of at least 12 months were all linked to a reduced likelihood of anxiety and depression. Each additional week of exclusive breastfeeding was associated with a small but significant reduction in risk.
Conclusion and Limitations
The study's findings indicate that breastfeeding, particularly longer exclusive and cumulative durations, was associated with a lower likelihood of anxiety and depression over a 10-year period. These results suggest a potential link between breastfeeding and long-term maternal psychological well-being, extending beyond the postnatal period. Potential explanations include the biological effects of lactation hormones, a reduced risk of metabolic disease, and protection against postnatal depression, which is a predictor of later mental health issues.
Strengths of the study include its long follow-up period, comprehensive dataset, and adjustment for multiple confounders. However, limitations include a small sample size and a relatively homogenous cohort from a single hospital in Dublin. Reliance on self-reported mental health and antidepressant medication use as a proxy for depression or anxiety may introduce bias, and due to the observational design, causality cannot be inferred. The possibility of unmeasured confounding also remains.