Recent advances in perinatal medicine and neonatal intensive care have significantly increased the survival rates of preterm newborns. The composition of breast milk varies as per obstetric, maternal, and infant-related factors like pre-pregnancy body mass index (BMI), maternal diet, and health conditions like diabetes or hypertension. Milk from mothers of the preterm infants, specifically those born extremely preterm, contains higher energy and protein levels. It is potentially supported to catch up on growth. In the lactation stage, any changes in the milk composition can be seen in the reduction in protein and elevation in fat. Evaluation of the nutritional content of breast milk is complex because of the variations in lactation stage and feeding patterns.
The Miris Human Milk Analyzer is a popular tool for the analysis of practical macronutrients. Targeted and adjustable fortification offers individualized nutritional support based on direct milk analysis or metabolic markers. However, current knowledge is not sufficient for understanding how neonatal and maternal factors influence the nutritional profile of breast milk. This review aims to compile comprehensive information on the many factors that can affect the energy and macronutrient content of breast milk, including obstetric, maternal, and newborn characteristics.
The study performed a literature search on breast milk composition, energy, carbohydrate, fat, protein, macronutrient, human milk, pregnancy morbidities, maternal factors, preterm infant, and preterm delivery. This search covered studies from May 2006 to May 2025, including those using the Miris Human Milk Analyzer. The reviews summarized current systematic reviews, including sample size, review type, methods used to evaluate milk energy and macronutrient content, limitations, and main findings.
This review analysed 35 studies to assess how obstetrical, maternal, and neonatal factors affect the energy and macronutrient composition of breast milk. Maternal factors demonstrated the most consistent and significant effects. Maternal nutritional status, stage of lactation, and dietary intake were the most frequently studied variables.
Socioeconomic status (SES) has a significant impact on milk composition. Mothers with lower SES produced milk with higher levels of n-9 and monounsaturated fatty acids. Whereas mothers with higher SES had greater levels of n-6 and n-3 polyunsaturated fatty acids, which reflect variations in dietary quality and food access. Food insecurity was associated with lower levels of amino acids, fat, and retinol in milk but increased lactose levels. Maternal profession also had an impact, with women working in the private sector having greater protein and fat content in milk composition than those in other professions. Cultural and geographic dietary patterns impacted the fatty acid profile of milk due to variations in the consumption of foods like saturated fats or fish.
Maternal age also influenced the composition. Older mothers tended to produce breast milk with more protein and fat, while younger mothers had high levels of n-6 fatty acids. Obese and overweight mothers produced milk with high fat and energy content. Favorable milk fatty acid profiles were linked to diets rich in fish and polyunsaturated fatty acids. Highly saturated fatty acids led to low favorable milk. Smoking consistently led to low protein and fat content in breast milk.
Circadian variation was detected with increasing fat levels in the evening. These results highlight the multifactorial and complex nature of breast milk composition. These needs further research to provide clinical and nutritional recommendations.
This review provides an in-depth analysis of variables that affect the energy and macronutrient composition of breast milk. It involved both current systematic reviews and original research, which allows for complex interpretation. Maternal factors like age, SES, diet, smoking, lactation stage, and galactagogues affect milk composition. At the same time, obstetric influences include delivery mode, hypertensive disorders, and preterm birth. The main finding is the association between maternal obesity and high energy and fat content in breast milk. Further research is needed to confirm these results.
References: Rocha-Pinto I, Pereira-da-Silva L, Silva D, Cardoso M. Factors that may affect breast milk macronutrient and energy content: A critical review. Nutrients. 2025;17(15):2503. doi:10.3390/nu17152503
