The complexity of human milk-feeding behaviours may not be captured using simpler definitions of "exclusive" and "non-exclusive" breastfeeding. New definitions have been suggested to describe variation in these behaviours more fully but have not been widely applied. We applied the new definitions to data derived from 3-day human milk-feeding diaries. Participants (n = 1091) recorded the number, beginning/end time, and modes of feeding of infants aged 3 months. Data were used to create six exclusive groups according to feeding mode(s): (1) human milk at-breast only; (2) human milk at-breast and human milk in a bottle; (3) human milk at-breast and infant formula in a bottle; (4) human milk at-breast and human milk and infant formula mixed in the same bottle; (5) human milk at-breast, human milk in a bottle, and infant formula in a bottle (not mixed); and (6) a bottle that sometimes contained human milk and sometimes infant formula (not mixed), never at-breast. Differences in maternal and infant characteristics were examined among groups. Fifty-seven percent fed at-breast only (Group 1). Those in Group 1 spent a similar amount of time feeding directly at-breast (median 132 (IQR 98-172) min/day) as those in Groups 2 (124 (95-158)), 3 (143 (100-190)), and 5 (114 (84-142)) (p > 0.05), indicating that adding bottle feeding did not always reduce the time infants were fed at-breast. Applying new suggested definitions to describe human milk-feeding behaviours from the mothers' perspective highlights the complexity of patterns used and warrants further application and research to explore impacts on health outcomes.
Keywords: bottle feeding; breastmilk feeding; expressed breastmilk; human milk; infant feeding behaviour.