Breastfeeding experience and milk weight in lactating mothers pumping for preterm infants

Background: Research about parity or breastfeeding experience and its relat ionship with milk production in humans is limited. The purpose of this stud y was to determine if any difference in milk volume occurred among mothers with and without breastfeeding experience who used either a single or doubl e breast pumping regimen the first 5 weeks postpartum. Methods: A convenien ce sample of 39 mothers of nonnursing preterm infants participated from two tertiary care centers in the midwestern United States. The sequential sing le pumping group consisted of 20 mothers, 7 of whom had previous breastfeed ing experience; the simultaneous double pumping group consisted of 19 mothe rs, 2 of whom had previous breastfeeding experience. Income and pumping gro up regimen were used as blocking variables, and average frequency of kangar oo care per week and average frequency of breast pumping per week were cova riants in the repented measures analysis of variance. Results: Mothers with previous breastfeeding experience had greater milk weights over time, but weights were nor significantly different when compared with those mothers w ith no previous breastfeeding experience. Additional analysis with the cova riants of pumping frequency and kangaroo care, and with the independent var iables of group, breastfeeding experience, and income resulted in statistic ally significantly greater milk yield in the women with previous breastfeed ing experience. Conclusions: The findings of the two repeated analyses indi cated the complexity of the milk production response, and the importance of considerations of environmental as well as physiologic factors.