A study conducted over ten years with Irish mothers indicates that breastfeeding may have long-term mental health benefits for women, potentially lowering the risk of depression and anxiety years after childbirth.
The research, published in BMJ Open, followed a group of women from a Dublin maternity hospital who were initially recruited during their second pregnancy. The study included 168 participants who provided complete data on both breastfeeding history and mental health at a ten-year follow-up. Women who were pregnant or breastfeeding at the time of follow-up were not included in the analysis.
Researchers assessed whether participants had ever breastfed, the duration of any and exclusive breastfeeding, and whether they had breastfed for at least 12 months in total. Mental health outcomes were determined through self-reported diagnoses of depression or anxiety as well as reported use of antidepressant medications, although reasons for medication use were not recorded.
The findings showed that 72.6% of women reported having breastfed at some point. The median duration for exclusive breastfeeding was 5.5 weeks, while any breastfeeding lasted a median of 30.5 weeks. More than one-third had breastfed for at least 12 months over their lifetime.
At the end of the study period, 13.1% reported depression or anxiety; this figure rose to 20.8% when considering any occurrence during the entire study period. Those reporting these conditions tended to be younger, have lower baseline well-being scores, smoke more frequently by study’s end, and were less likely to have breastfed or to have done so for as long.
After adjusting for differences such as age, baseline well-being, physical activity, and alcohol intake, researchers found that having ever breastfed was linked to lower odds of experiencing anxiety or depression ten years later. Longer periods of exclusive breastfeeding and cumulative durations over twelve months also correlated with reduced risk across the full study period.
The authors noted several possible explanations for these results: "Biological mechanisms underlying this relationship may involve lactation hormones such as oxytocin, which promotes bonding, reduces anxiety, and supports stress regulation through the hypothalamic-pituitary-adrenal axis." They also suggested that reduced risk of metabolic disease and protection against postnatal depression could play roles.
Despite strengths like its long-term design and detailed dataset accounting for multiple confounders in a healthy population sample, limitations include its small size and lack of diversity—participants all came from one Dublin hospital—and reliance on self-reported mental health information along with antidepressant use as an outcome measure. Because it was observational in nature rather than experimental, causality cannot be established definitively.
"Overall," according to the researchers’ summary statement in BMJ Open,"the findings suggest that breastfeeding may be associated with a reduced risk of long-term maternal mental health problems and highlight the need for larger, more diverse studies to validate these associations."
