Pregnancy gestation at delivery and breast milk production: a secondary analysis from the EMPOWER trial.

Background: Preterm birth alters the normal sequence of lactogenesis. Lactogenesis I may not yet have started when mothers of very preterm infants (≤ 29 weeks gestation) have given birth. Preterm infants are too small or too ill to initiate suckling in the immediate postpartum period thus altering the normal cascade of event for lactogenesis II. With an increasing demand for mother's own milk as a primary source of nutritional support in the care of very small and preterm infants, mothers of these infants are often at risk of expressing inadequate amounts of milk. The use of galactogogues is often considered when mothers of preterm infants are still having challenges in breast milk production. What is not clear in the literature is the role that pregnancy gestation at birth plays in successful response to galactogogues. Our objective for this study was to evaluate the role of pregnancy gestation at birth on a mother's response to the treatment interventions in the EMPOWER trial.

Methods: For this analysis, the study participants are the 90 mothers who participated in the EMPOWER trial and were in the stratified in two gestational age groups, 23^0/7-26^6/7 weeks and 27^0/7-29^6/7 weeks at the time of randomization. The primary outcome measures were the proportion of mothers in each of the gestational age groupings who achieved a 50% increase in breast milk volume on day 14 and day 28 of the study treatment period.

Results: On day 14 of the study treatment, there was no significant difference in the proportion of mothers in the 23-26 weeks gestation group (72.9%) compared to those in the 27-29 weeks gestation group (64.2%), OR 1.51 (95% CI 0.60, 3.78; p = 0.38). Similarly, there was no difference in the proportion of mothers between the two gestational age groupings on day 28 of the study treatment, 70.3% compared to 62.3%, OR 1.43 (95% CI 0.58, 3.51; p = 0.43).

Conclusion: This secondary analysis was able to demonstrate that mothers of very preterm infants, < 30 weeks gestation at birth, were able to respond to the study treatment in a similar fashion regardless of gestation at birth. If non-pharmacologic approaches are unsuccessful, then a 14-day treatment of domperidone may be considered to enhance breast milk production, even in the lowest gestational ages at delivery.

Trial registration: EMPOWER has been registered at www.clinicaltrials.gov (identifier NCT 01512225) on January 10, 2012.