Frequency of Milk Expression Among Mothers with Very Low Birthweight Infants
by Anne Eglash MD, IBCLC, FABM
For lactating individuals whose babies cannot directly breastfeed, the World Health Organization recommends expressing milk at least 7 times in 24 hours including at least once at night. These recommendations are based on evidence from feeding patterns of term infants and there is little research on the optimal frequency of milk expression for mothers whose infants are premature or very low birthweight.
Researchers for this week’s study analyzed data from a randomized controlled trial of 132 people in 4 neonatal units in the United Kingdom who had given birth to 1 or 2 infants between 23 and 31 6/7 weeks gestation, in 2021 and 2022. The participants measured 24-hour milk expression volume on days 4, 14, and 21 postpartum.
They found that the frequency of milk expression and the duration of the longest gap between expressions are associated with milk production.
What else? See the question!
- The differences in milk expression volumes among participants were 90% related to frequency of milk expression.
- Taking a longer break between milk expressions, unrelated to milk expression frequency, was associated with less milk removal.
- Expressing 8 or more times a day was not associated with significantly higher 24-hour milk yield than expressing 6-7 times a day.
- Study participants with a history of lactation for >6 months in the past were able to express less often to achieve the same milk yield as primiparous participants.
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Abstract
Introduction
Mothers of very premature infants often have difficulties expressing breastmilk, which can cause distress and potential negative impact on infant health. Clinical recommendations on breastmilk expression are extrapolated from term infants’ breastfeeding patterns. This study’s objective was to analyse the association of expressing pattern with lactation outcomes after very premature birth.
Methods
132 participants were recruited after birth between 23+0 and 31+6 weeks’ gestation. Participants recorded the milk expressed in several 24-hour periods in the three weeks after birth.
Results
Expressing frequency was positively associated with 24-hour milk yield, with an adjusted 30.5g increase per expressing session on day four (95% CI 15.7 to 45.3) and 94.4g on day 21 (95% CI 62.7 to 126.2). Expressing > 8 times per day was associated with higher adjusted milk yield than expressing <6 times (on day four, 146.8g, 95% CI 47.4 to 246.1) but not in comparison to expressing 6-7 times (on day four 82.1g, 5% CI -25.9 to 190.1). Participants with six months or more prior breastmilk feeding experience had a higher adjusted milk yield than others (on day four, 204.3g, 95%CI 125.2-283.3). Night-time (2300-0700 hours) expression sessions were not associated with increased milk yield after adjustment for time since the prior session. On average, participants who had a longest gap between expressions of less than six hours achieved the UK target of 750g breastmilk, whereas those with a longer gap did not.
Conclusions
Expressing frequency was an important determinant of milk yield. Clinical recommendations to express ≥8 times per day were supported but for some, 6–7 times was sufficient. This was particularly likely for those with six months or more of prior breastmilk feeding experience. A need to express during the night-time hours appeared to be related to minimizing the gap between expressions rather than an inherent value of nighttime expression.
The researchers basically found that their results support the United Kingdom clinical recommendations to express milk at least 8 times a day with at least 1 expression overnight for mothers whose babies are premature or low birth weight. The findings also supported less than a 6-hour gap between milk expression sessions. The results demonstrated a 30ml/hour decrease in milk yield for each hour increase in the longest gap between expressions on day 21.
Expressing milk 8 times a day was associated with 163.8 ml greater yield/day on day 21 as compared to expressing 6-7 times a day, however this amount was not considered statistically significant. Expressing less than 6 times a day was associated with 402.1ml less milk yield/day on day 21 as compared to expressing > 8 times a day. Therefore, milk expression of at least 6-7 times a day, and ideally 8 times a day would help maximize milk production.
Milk expression frequency only accounted for 8-22% variability in milk yield between study participants. This makes sense, since we know there are many other factors that play a role in rate of milk production besides expression frequency and time between expressions, such as parental health conditions, pump settings, flange size, medications, etc.
Pat Rizzo
Nice concise information for NICU mothers.
Nikki Lee
163.8 ml difference between 6-7 pumps/day and 8 pumps/day at 3 weeks may not have been statistically. significant….but that is a 5+ounce a day difference. That could be significant clinically, both on a day to day basis and potentially at a later time.
The article is important as it promotes flexibility in our care.