Maternal medications lower the protein and fat levels in breast milk: JAMA

A recent study published in the Journal of American Medical Association highlighted the potential impact of maternal medications on the macronutrient composition of human milk. This cross-sectional study examined breast milk samples from mothers in the US and Canada who were either on long-term medications, untreated but with the same underlying health conditions, or completely healthy.

The study by Essi Whaites Heinonen and at the University of California, San Diego analyzed milk samples collected from October 2014 to January 2024 as part of the Mommy’s Milk Human Milk Research Biorepository. This research compared macronutrient levels (protein, fat, carbohydrates, and total energy) in milk samples from 310 mothers on medications, 151 untreated mothers with similar health conditions (disease-matched controls , or DMCs), and 73 healthy untreated mothers. The medications studied included selective serotonin reuptake inhibitors (SSRIs), monoclonal antibodies (MABs), systemic steroids, and other anti-inflammatory drugs (ADs).

After excluding samples with multiple medication exposures or extreme outliers, a total of 384 samples remained for analysis. The team adjusted their findings for several variables, including maternal and infant age, maternal body mass index, breastfeeding practices and other relevant factors. The study found that breast milk from mothers taking certain medications showed significantly lower levels of protein and fat when compared to healthy mothers.

The samples from mothers using SSRIs and systemic steroids showed a 15% to 21% reduction in protein levels when compared to healthy mothers. For instance, milk from mothers on SSRIs contained 0.92 g/100 mL of protein on average when compared to 1.08 g/100 mL in samples from healthy mothers. These differences were statistically significant (P = 0.04 for SSRIs and P = 0.03 for steroids).

The fat levels in milk from mothers on other anti-inflammatory drugs were 10% to 22% lower than the milk from healthy and DMC mothers. Milk from mothers on these medications contained an average of 3.40 g/100 mL of fat, when compared to 3.85 g/100 mL in healthy mothers and 4.38 g/100 mL in DMCs. Also, the energy levels were reduced with treated the milk of mothers in averaging 69.56 kcal/100 mL, versus 77.16 kcal/100 mL in healthy mothers. The difference in fat content compared to DMCs was particularly significant (P = 0.01).

These findings suggest that certain maternal medications may affect the nutritional quality of breast milk, potentially posing risks to the growth and development of infants. The outcomes emphasize the need for further research to identify other contributing factors and fully understand the clinical implications.

Source:

Whaites Heinonen, E., Bertrand, K., & Chambers, C. (2025). Macronutrients in Human Milk Exposed to Antidepressant and Anti-Inflammatory Medications. In JAMA Network Open (Vol. 8, Issue 1, p. e2453332). American Medical Association (AMA). https://doi.org/10.1001/jamanetworkopen.2024.53332