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.