The Effect of Different Pumps on Secretory Activation Among Mothers of Preterm Infants
by Anne Eglash MD, IBCLC, FABM
Is a hospital grade pump more effective than a personal electric pump in establishing milk production among mothers with premature infants?
There is little research on pumps such that lactating parents’ only recourse is to follow advice from friends, family, lactation specialists and social media influencers/groups. Unfortunately, some social media influencers and lactation specialists are conflicted because they receive financial kickbacks from pump companies.
Pumps vary widely in terms of their cycle wave forms, frequencies and vacuum settings, and we have no evidence as to which pump is best for whom.
The authors for the study this week sought to determine whether a hospital grade pump was more effective than a personal double electric pump in establishing healthy milk production in the first 2 weeks postpartum among 66 mothers of preterm infants at a hospital in China in 2018. All participants gave birth to infants at 28-35 weeks gestation and intended to breastfeed. The mothers were randomized into 3 groups: Group 1 used a hospital grade electric breast pump for days 1-14; group 2 used a hospital grade electric pump for days 1-5 and a personal electric breast pump on days 6-14; group 3 used a personal electric breast pump on days 1-14. The researchers report that all mothers were given evidence-based lactation care and support by NICU nurses, including education on pumping by 1 hour postpartum.
The researchers tracked the volume of expressed milk and measured the sodium level in milk samples twice a day for 14 days, to determine timing of secretory activation. They found that mothers who used the hospital grade pump for 14 days had average milk volumes on day 14 of approximately 825ml/day, similar to those who used the hospital grade pump for the first 5 days only. The group that didn’t use a hospital grade pump had an average volume of approximately 500ml/day on day 14.
The researchers didn’t provide data on pump qualities, such as cycle frequency and vacuum, nor details on flange fitting. They also didn’t report the number of pump sessions per day.
What else? See the question!
- Higher volumes of expressed milk were associated with lower milk sodium levels.
- Mothers who did not use the hospital grade pump had the highest milk sodium levels.
- The milk sodium levels had no correlation with milk volume expressed.
- The mothers who used a hospital grade pump, either for 5 or 14 days, no longer had high milk sodium levels after day 4 postpartum.
See the Answer
This study investigated changes in sodium concentrations in human milk from mothers of premature infants using different breast pumps for 14 days postpartum, and the correlation between the sodium concentration in mother’s own milk (MOM) and the volume pumped.
This randomized controlled study recruited 66 mothers of premature infants delivered in our hospital from February to December 2018, and we assigned them to three groups using an envelope method. In intervention group 1, a hospital-grade electric breast pump was used from postpartum day 1 to 14; in intervention group 2, a hospital-grade electric breast pump was used on postpartum days 1 to 5 and a normal personal electric breast pump on postpartum days 6 to 14; in the control group, a personal normal electric breast pump was used from postpartum day 1 to 14. Data recorded included the breast milk volume pumped and milk sodium concentration.
The average daily volume of MOM pumped differed statistically ( p <0.05) between the intervention and control groups at postpartum days 7 and 14. The average daily volume pumped did not differ between intervention groups 1 and 2 by postpartum day 14 ( p >0.05). However, the time taken for the sodium concentrations to normalize differed signiﬁcantly ( p <0.01). At postpartum day 5, the sodium concentrations of 73% of intervention group 1 and 2 mothers were within normal limits, and they were maintained until day 14. In comparison, only 41% of the controls had normal MOM sodium levels on day 5, and they were still high on day 7 in 27.3% of controls.
In the early stage of lactation initiation (within 5 days postpartum), using a hospital-grade electric breast pump promotes lactation in mothers who deliver prematurely and the sodium concentrations normalize more quickly. Sodium can be used as an objective biomarker of MOM to evaluate the possibility of delayed lactation in mothers of premature infants, and it could assist interventions in the early postpartum period.
Let's do a quick review of milk sodium levels. After birth, the space (paracellular pathways) between the milk-producing cells (lactocytes) are open, allowing sodium in the mother’s blood stream to move into the milk producing glands (alveoli) causing a higher sodium level in colostrum as compared to transitional or mature milk. As the progesterone level drops postpartum and prolactin remains high by nursing or pumping, the spaces between the cells close because proteins called tight junctions become well organized. Once the tight junctions are sturdy, sodium from the mother’s blood stream can no longer move freely into the milk space. This causes the sodium level to decrease to the level needed by the suckling infant. The sodium level is essentially a marker for ‘the milk coming in’ (secretory activation). It is a more accurate measure than judging the onset of secretory activation by asking mothers about breast changes.
The researchers found that the milk sodium level dropped more quickly among mothers who had a rapid rise in milk production postpartum. The mothers who didn’t use a hospital grade pump and relied on a personal electric pump had the slowest rise in milk production over time, and therefore had higher milk sodium levels for a longer period of time.
Research on pumps needs improvement. It is time for peer reviewed journals to require more stringent guidelines on the definition of pumping, such as vacuum settings, cycle frequencies, method of flange fitting, and pain scores with pumping. This particular study has major limitations because they did not define pumping, report frequency of pumping, nor did they report any measures of pain scores related to pumping, all of which play a role in volume of milk expression.