Association between expressed breast milk feeding and breastfeeding duration in Hong Kong mothers

Expressed breast milk feeding has increased substantially in the past two decades. Once used primarily for preterm infants, feeding expressed breast milk is now more common in mothers giving birth to healthy term infants. However, the effect of expressed breast milk feeding on breastfeeding duration is unclear.

To assess the association between breast milk expression practices and breastfeeding duration in women giving birth to healthy infants.

From 2017 to 2018, we recruited 821 new mothers from two public hospitals in Hong Kong. Participants were followed up at 1.5, 3, and 6 months postpartum or until they stopped breastfeeding. The proportion, type, and mode of all milk feeding were assessed at each follow-up.

At 1.5 months postpartum, 47.9%, 37.7%, and 14.4% of participants were feeding by direct breastfeeding only, mixed-mode feeding, and expressed breast milk only, respectively. Participants feeding expressed breast milk only were more likely to be supplementing with infant formula. When compared with participants who provided only direct breastfeeding, participants who gave only expressed breast milk at 1.5 months had 57% lower odds of breastfeeding continuation at three months postpartum. After stratification by infant formula supplementation, expressed breast milk feeding only at 1.5 months was associated with an increased risk of breastfeeding cessation in participants supplementing with infant formula (adjusted hazard ratio [aHR] = 1.86, 95% CI = 1.17-2.95).

In the first six months postpartum, giving only expressed breast milk is associated with early breastfeeding cessation, especially in participants who are also supplementing with infant formula.