But fear not, as the reduced protein and fat levels are unlikely to affect infant growth or development.
Medication-affected breast milk may not be best, but it’s still fine to use, experts say, as infants can compensate for lower nutrient levels with extra feeding.
Research suggests that over 70% of breastfeeding women take some kind of medication, yet little is known about whether and how certain prescription medications affect the macronutrient concentration of breast milk.
A new study, believed to be the first of its kind, reports that breastfeeding women exposed to SSRIs, steroids or anti-inflammatory drugs had 20-30% reductions in the protein or fat content of their breast milk compared to controls. The findings were published in JAMA Network Open.
“In this cross-sectional study, some maternal medications were associated with lower levels of protein and fat in milk, which could impose health risks for breastfed infants,” the study authors concluded.
“[However,] other factors that could influence macronutrient levels need to be clarified before the clinical implications of these findings can be confirmed.”
Researchers analysed the macronutrient levels of breast milk samples from 384 women: 63 were exposed to SSRIs, 63 to monoclonal antibodies, 33 to systemic steroids and 20 to other anti-inflammatory drugs; 141 had an inflammatory and/or mood disorder but were not receiving treatment (serving as a disease-matched control group) and 64 were healthy, unmedicated controls.
After controlling for factors such as maternal ethnicity, maternal and infant age at sample collection, the sex of the baby and whether the mother was breastfeeding exclusively or supplementing with formula and/or other solid foods, women taking SSRIs and steroids had milk protein levels that were 20% and 31% lower compared to the healthy control women. Women taking anti-inflammatory drugs had fat levels that were 26% lower compared to the disease-matched controls.
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There was no association between prescription medication use and carbohydrate or total energy levels in the breast milk samples after adjusting for relevant covariates.
The study authors acknowledged the differences in fat and protein levels could potentially affect infant growth and their longer-term health if any abnormalities were not caught by routine check-ups but emphasised there was no cause for concern.
“As the mean macronutrient levels were within normal range in all exposure groups, these results should not affect the breastfeeding recommendations for mothers treated with antidepressants and anti-inflammatory medications, and the growth of their breastfed infants should be monitored as per clinical routine,” they wrote.
“It is likely that healthy infants would compensate for these lower levels of nutrients in human milk with intensified feeding, leading to increased milk production.”