Tandem Breastfeeding and Human Milk Macronutrients: A Prospective Observational Study

Background: Tandem breastfeeding is defined as two or more offspring of different ages who are breastfed by their mother at the same time. Breastfeeding during pregnancy and tandem breastfeeding have not been widely investigated. Research Aim: To determine the influence of tandem breastfeeding on the macronutrient content of human milk. Methods: This longitudinal study used a prospective and a retrospective group. Human milk samples from tandem-breastfeeding participants (n = 18) were compared to samples from non-tandem-breastfeeding participants (n = 31). Samples were collected during the last month of pregnancy (pregnancy milk), 72 hr after birth (colostrum) and 14–60 days post-delivery (mature milk). Macronutrients were measured by mid-infrared spectroscopy. Results: Fat content in pregnancy milk was lower than in mature milk (p <.01). Protein content was higher in pregnancy milk than in colostrum and mature milk (p <.01 and p <.001, respectively). Inversely, carbohydrate content in pregnancy milk was lower than in colostrum and mature milk (p =.02 and p <.01, respectively). Fat and energy contents in pregnancy milk of tandem-breastfeeding participants were lower than in mature milk of non-tandem-breastfeeding participants (p <.001 and p <.01, respectively), and protein content was higher than in mature milk (p <.001). Carbohydrate content in colostrum and mature milk of tandem-breastfeeding participants was higher than that of non-tandem-breastfeeding participants (p <.001 for both). Conclusion: Human milk produced during pregnancy had different macronutrient content than human milk produced after delivery. Colostrum and mature milk of tandem-breastfeeding participants were similar to human milk produced by non-tandem-breastfeeding participants, with the exception of carbohydrate content.