Mother–infant sleep proximity & breastfeeding in evolutionary perspective

I'm excited today to announce the AJPA early view appearance of Evolutionary perspectives on mother–infant sleep proximity and breastfeeding in a laboratory setting by University of Notre Dame professor Dr. Jim McKenna and Northwestern doctoral candidate Lee Gettler.


Keywords:breastfeeding;bedsharing;cosleeping;human evolution
Abstract
Human maternal and infant biology likely coevolved in a context of close physical contact and some approximation of frequent, “infant-initiated” breastfeeding. Still, mothers and infants commonly sleep apart from one another in many western societies, indicating a possible “mismatch” between cultural norms and infant biology. Here we present data from a 3-night laboratory-based study that examines differences in mother–infant sleep physiology and behavior when mothers and infants sleep together on the same surface (bedsharing) and apart in separate rooms (solitary). We analyze breastfeeding frequency and interval data from the first laboratory night (FN) for 52 complementary breastfeeding mothers and infants (26 total mother–infant pairs), of which 12 pairs were routine bedsharers (RB) and 14 were routine solitary sleepers (RS). RB infants were 12.0 ± 2.7 (SD) weeks old; RS infants were 13.0 ± 2.4 weeks old. On the FN, RB mother–infant pairs (while bedsharing) engaged in a greater number of feeds per night compared to RS (while sleeping alone) (P < 0.001). RB also showed lower intervals (min) between feeds relative to RS (P < 0.05). When we evaluated data from all three laboratory nights (n = 36), post hoc, RB breastfed significantly more often (P < 0.01) and showed a trend towards lower intervals between feeds (P < 0.10). Given the widely known risks associated with little or no breastfeeding, the demonstrated mutually regulatory relationship between bedsharing and breastfeeding should be considered in future studies evaluating determinants of breastfeeding outcomes.

p.s. I'm a bit behind in my "awesome" posts. I hope to get caught up on new BANDIT publications over the break.