Dietary shifts during lactation: a prospective birth cohort

Breastfeeding is the optimal source of nutrition for infants, supporting their healthy development. Maternal diet during breastfeeding is associated with human milk (HM) composition and may provide an opportunity to reduce infants’ risk of conditions such as eczema and food allergies. Thus, it is critical to understand changes in maternal diet during the postpartum period. To explore maternal diet variation during lactation. In a nested substudy within the PRIMA birth cohort, maternal diet was assessed using food frequency questionnaires (FFQs) at two and four months postpartum. Changes in food groups and nutrients over time were examined using a linear mixed model, considering breastfeeding and feeding practices and work status. FFQs were obtained from 226 healthy lactating mothers, of whom 170 filled out the complete FFQs at both time points. Mothers adhered to the Dutch dietary guidelines, with a mean ± standard deviation decrease in energy intake at four months compared with two months postpartum (2106 ± 616 vs. 2220 ± 621 kcal/day; p < 0.05). We found no differences in intake for most food groups, adjusted for energy intake, over time. Intake of alcoholic beverages increased from two to four months postpartum (p < 0.001). Consumption of food groups containing major food allergens was stable for eggs, nuts, and seeds, whereas intake of milk and milk products decreased over time (p < 0.01). Milk and milk product intake was dependent on breastfeeding and feeding practices, with exclusively breastfeeding mothers consuming less than mothers who combined breastfeeding with formula feeding (p < 0.001), independent of timing. Postpartum diets of mostly highly educated women are relatively stable, except for changes in the intake of specific food groups, and correlate with breastfeeding and feeding practices. These shifts should be considered when studying maternal diet’s association with HM composition, specifically with regard to maternal allergen intake and its potential effect on infants’ risk of allergies.