Short-term rate of milk synthesis and expression interval of preterm mothers

Aim To determine the impact of the pumping regimes of women with preterm infants on the daily milk production, and on the short-term rate of milk synthesis during early lactation to support evidence-based recommendations for optimising milk production. Methods Mothers of preterm infants (n=25) recorded start time, finish time and expression volumes from every breast expression on days 10, 15-20 postpartum. Results Expressing more often than five times per day did not result in a significant increase in daily milk production. Milk volume per expression per breast increased for intervals between expressions of between 2and6 hours then reached a plateau when the interval between expression was 7 hours or longer. The short-term rate of milk synthesis decreased as the interval between expressions increased until about 7.5 hours at which point it begun to increase (p value associated with interval between expressions^2<0.001). Conclusion The strong inverse association between the short-term rate of milk synthesis and the interval between expressions for intervals up to 7 hours suggest that the maximum interval between expressions should be 7 hours. Data suggest that, on average, the mothers should express at least five times a day to maximise daily milk production. Considering inter-individual variation, determination of an individual mother's maximum interval between expressions that does not compromise the short-term rate of milk synthesis will help to optimise daily milk production while minimising the demands on the mother's time.