Journal of Perinatology (2016) 36, 47–51 © 2016 Nature America, Inc. All rights reserved 0743-8346/16 www.nature.com/jp
ORIGINAL ARTICLE
Milk production after preterm, late preterm and term delivery; effects of different breast pump suction patterns EDM Post1, G Stam1 and E Tromp2 OBJECTIVE: This study aimed to compare the effectiveness of two different breast pump suction patterns (BPSP) during the initiation of lactation in mothers of term, late preterm and preterm infants. METHODS: Breast pump-dependent mothers (n = 130) of term (n = 19), late preterm (n = 44) and preterm (n = 67) infants were assigned to either a standard or irregular-BPSP after birth until the onset of secretory activation. Both groups used the same standard maintenance BPSP thereafter. Time to secretory activation, time to full milk production and daily milk output were compared between the standard and I-BPSP groups, and between the term, late preterm and preterm groups. RESULTS: Mothers using the irregular-BPSP demonstrated significantly greater daily milk output and established secretory activation significantly earlier. This effect was observed in mothers of term, late preterm and preterm infants. CONCLUSION: The irregular-BPSP mimicking sucking of healthy newborns is more effective at achieving secretory activation and an earlier adequate milk supply than the standard-BPSP. The irregular-BPSP can be used successfully for mothers of preterm up to term infants who are breast pump dependent during the establishment of lactation. Journal of Perinatology (2016) 36, 47–51; doi:10.1038/jp.2015.152; published online 5 November 2015
INTRODUCTION Human milk provides the infant with protection against infection and chronic disease and promotes optimal growth and development in a dose-response manner.1,2 However, many mothers of preterm or ill infants who are breast pump dependent, experience difficulties initiating and maintaining an adequate milk supply for their infant during the early post-partum period. The etiology of problems initiating and maintaining lactation in this population is multicausal.3 Mothers of preterm infants often experience difficulty initiating lactation due to their earlier stage of breast development, lack of infants’ sucking contact, emotional challenges resulting from preterm delivery and poor access to appropriate equipment and timely support.4 Nearly all mothers of preterm infants experience significant stress, anxiety and lack of sleep during the first weeks after delivery, which can further compound the initiation and maintenance of lactation.5,6 During the initiation of lactation, healthy breastfeeding infants demonstrate periods of milk removal (nutritive sucking); characterized by slower suck rates, and longer bursts as well as periods devoid of milk removal (non-nutritive sucking); characterized by rapid suck rates, and strong vacuums over short bursts. During the breastfeeding episode the infant therefore demonstrates variations in their suck rates, vacuum levels and suck bursts.7–12 After secretory activation, infants utilize a more biphasic sucking pattern with a larger proportion of time spent removing milk (nutritive sucking) than non-nutritive sucking, along with a higher rate of milk flow, and slower suck rates.12 It is therefore plausible that pumping patterns that mimic these breastfeeding patterns during the initiation and maintenance of lactation can improve milk output during pumping. Mothers of healthy term infants have demonstrated effective milk removal using a standard breast pump suction pattern (S-BPSP). The S-BPSP consists of two phases aiming to mimic a term breastfeeding infant during established
lactation. The first phase (stimulation phase) mimics the infant’s behavior before milk ejection with a regular rapid sucking rate. The second phase (expression phase) resembles the infant’s sucking after the milk ejection with a slower sucking rate.13–15 More recently, breast pump-dependent mothers of premature infants o 34 weeks gestational age (GA) have demonstrated more effective milk removal when using breast pump suction patterns that mimic irregular-BPSP (I-BPSP) during the initiation of lactation.7 This pattern was based on the fact that healthy infants in the first post-partum days, before the onset of secretory activation, exhibit minimal milk flow with a mix of rapid and irregular sucking patterns. Using this pattern, mothers of preterm infants demonstrated an improved total volume of milk output and milk removal per minute. As a result, these special pumping patterns are now commonly advised to mothers pumping for a premature infant. However, it is unknown if these patterns are also preferable for mothers from late preterm and term infants. This study aimed to determine if the I-BPSP would improve milk output in pump dependent mothers who delivered prematurely, closer to term and at term. In particular, we hypothesized that the I-BPSP would be more effective than the S-BPSP at improving milk output in pump-dependent mothers of not only preterm but also late preterm and at term infants. METHODS Study design An observational study design was used to compare the effectiveness of the S-BPSP and the I-BPSP initiating lactation. The study was approved by our Medical Research Ethical Committees United. Pump dependent mothers who delivered premature or more at term infants in our hospital between November 2010 and November 2012 were recruited to the study after consenting to the use of their breastmilk pumping data and infant
1 Pediatric Department, St Antonius Hospital, Nieuwegein, The Netherlands and 2Department of Epidemiology and Statistics, St Antonius Hospital, Nieuwegein, The Netherlands. Correspondence: EDM Post, Pediatrician, St Antonius Hospital, Postbus 2500, Nieuwegein 3430 EM, The Netherlands. E-mail:
[email protected] Received 27 March 2015; revised 20 September 2015; accepted 24 September 2015; published online 5 November 2015
Different breast pumping patterns; effects preterm to term EDM Post et al
48 Inclusions (130)
Non NICU (79)
Admitted to NICU (51)
37 weeks (3)
34-36 6/7 weeks (7)
S-BPSP (7)
I-BPSP (0)
S-BPSP (2)
I-BPSP (1)
37weeks (16)
S-BPSP (5)
I-BPSP (11)
Flow diagram of the study population.
Mother-infant characteristics S-BPSP (n = 64)
Mean gestational age (in weeks) ⩾37w GA 34–36 6/7w GA o34w GA Primipara Multiples Mean birth weight (in grams) Admitted on NICU ⩾ 37w GA 34–36 6/7w GA o34w GA Mean duration of admittance (in days)
I-BPSP (n = 66)
32.2 (24 6/7– 35 35.1 (36–41 6/7, s.d. 3.8) 3/7, s.d. 2.4) 11% (7) 18% (12) 20% (13) 47% (31) 69% (44) 35% (23) 69% (34) 79% (44) 31% (15) 21% (12) 1813 (s.d. 845) 2309 (s.d. 581) 78% (50) 4% (2) 14% (7) 82% (41) 38 (s.d. 25.6)
2% (1) 100% (1) 0% (0) 0% (0) 16 (s.d. 7.3)
Po0.001 Po0.001 P = 0.283 Po0.001 Po0.001 NA Po0.001
Abbreviations: I-BPSP, irregular breast pump suction pattern; NA, not available; S-BPSP, standard breast pump suction pattern; NICU, Neonatal Intensive Care Unit.
data. Mothers who were breast pump dependent for at least 7 days and pumped for 7 or more times a day were included in the study. No mothers were excluded on the base of medical conditions, perinatal complications or other lactation-related risk factors. Almost all mothers with an infant in the Neonatal Intensive Care Unit (NICU) (50/51) started pumping with S-BPSP because of the absence of I-BPSP pumps in the hospital with the NICU. One mother with a child in the NICU who delivered in our hospital pumped with I-BPSP. Criteria for NICU admission were prematurity o32 weeks GA, severe respiratory problems or perinatal asphyxia. The mothers with infants in our neonatal ward (n = 79) were randomly assigned to either the I-BPSP or S-BPSP depending on what suction pattern card was available at the start of their pumping period; in total 66 initiated with I-BPSP (I-BPSP group) and 64 with S-BPSP (S-BPSP group). Within several hours after delivery all mothers received standardized pumping instructions and the suction pattern card (either for I-BPSP or S-BPSP) for their breast pump. The lactation support for NICU and for nonNICU mothers was equal. Mothers were instructed to begin pumping within 4 to 6 h after birth, pumping both breasts simultaneously eight times a day (24 h) for 15 min until the daily total milk output was at least 50 ml (the onset of secretory activation). After the onset of secretory activation mothers who were using the I-BPSP switched to the S-BPSP and mothers already using the S-BPSP from initiation continued with this pattern as long as pumping was necessary. Data were collected by the mothers up to 14 days after delivery. Blinding to the group allocation was not possible as the mothers experienced the irregular or regular pumping patterns clearly.
Pumping patterns S-BPSP: The standard breast pump suction pattern (S-BPSP) is a two-phased suction pattern (Standard 2.0, Medela, Baar, Switzerland), consisting of a Journal of Perinatology (2016), 47 – 51
stimulation phase with rapid sucks (120 per min) for 2 min (or shorter if overridden by the breast pump user), and an expression phase with a slower rate of 60 events per minute. I-BPSP: the irregular breast pump suction pattern (I-BPSP) (Preemie+, Medela, Baar, Switzerland) used periods of 60, 90 or 120 sucks per minute, as well as pauses in suction randomly distributed in time. I-BPSP was only used shortly after giving birth until the onset of secretory activation.
Measures Milk output was recorded by mothers after each pumping session. The effectiveness of pumping was evaluated using two variables: the percentage of mothers that achieved an adequate milk supply (defined as a total daily milk output of 4500 ml within 14 days of delivery) and the day this target was reached for the first time.
Statistical analysis Statistical analyzes were performed using SPSS 22.0 (SPSS, Chicago, IL, USA). Differences in mother–infant characteristics between the I-BPSP and S-BPSP group were analyzed using χ2 tests or Fisher’s exact test for dichotomous variables (dichotomous variables: primipara vs multipara; preterm ( o34w GA) vs late preterm (34 to 36 6/7w GA) vs term (⩾ 37w GA) infants; admitted in NICU yes vs no) and independent Student's t-test for continuous variables (continuous variables: mean gestational age, mean birth weight and mean duration of admittance). Differences in daily milk production, time to initiation of secretory activation (50 ml per day), time to achieving an adequate milk production (500 ml per day), percentage of mothers in which production was deemed adequate (500 ml per day) between the S-BPSP and I-BPSP group, was tested using linear regression with and without adjustment for gestational age. The analyses of linear regression were performed using the total study population, and also after splitting the study population into preterm (o34w GA), late preterm (34 to 36 6/7w GA) and term ( ⩾ 37w GA) infants. Results were tested at a significance of Po 0.05.
RESULTS Mother-infant characteristics There were 67 mothers in the study who delivered at o34 weeks GA and 44 at 34 to 36 6/7 weeks GA (Figure 1). The mean duration of pumping records was 12.7 days (s.d. 2.4). Pumping was terminated when the infant was fully breastfed or when mothers chose for artificial feeding. Several mothers with inadequate milk supply terminated pumping and breastfeeding in the second week; 7.8% in the S-BPSP group and 4.5% in the I-BPSP group (P = 0.438, n = 8). Infants in the S-BPSP group had higher rates of NICU admission, lower gestational age, lower birth weight than the I-BPSP and mainly therefore longer length of stay in the hospital (P o 0.001, Table 1). Extended hospital stays for the ‘nonNICU’ babies were mainly due to infections, feeding- or respiratory problems. © 2016 Nature America, Inc.
Different breast pumping patterns; effects preterm to term EDM Post et al
49 Table 2.
Lactation results after initiating in the S-BPSP and I-BPSP group
Day post partum when production of 450 ml per day ( = start secretory activation) is reached (in days) n = 130
Difference between S-BPSP and I-BPSP group, adjusted for gestational age (95% CI)
S-BPSP I-BPSP
4.5 (s.d. 2.1) 3.3 (s.d. 0.6)
1.2 (0.7–1.7)*
1.1 (0.5–1.7)*
⩾ 37w GA
S-BPSP I-BPSP S-BPSP I-BPSP S-BPSP I-BPSP
4.0 3.3 4.4 3.4 4.6 3.3
0.7 ( 0.1–1.4)
0.6 ( 0.1–1.4)
1.0 (0.1–2.0)*
1.0 (0.1–2.0)*
1.4 (0.5–2.2)*
1.2 (0.1–2.3)*
Total
S-BPSP I-BPSP
9.5 (s.d. 3.0) 7.7 (s.d. 2.4)
1.8 (0.7–3.0)*
1.3 (0.1–2.5)*
⩾ 37w GA
S-BPSP I-BPSP S-BPSP I-BPSP S-BPSP I-BPSP
7.5 7.0 9.4 7.7 9.9 8.0
0.5 ( 2.0–3.0)
0.5 ( 2.1–3.0)
1.7 ( 0.3–3.6)
1.6 ( 0.3–3.6)
1.9 (0.1–3.7)*
0.9 ( 1.4–3.1)
Total
S-BPSP I-BPSP
53 (s.d. 50) 94 (s.d. 24)
41 (27–54)*
38 (23–53)*
⩾ 37w GA
S-BPSP I-BPSP S-BPSP I-BPSP S-BPSP I-BPSP
57 (s.d. 53) 100 (s.d. 0) 61 (s.d. 51) 94 (s.d.25) 50 (s.d. 51) 91 (s.d. 29)
43 (11–75)*
42 (9–75)*
32 (10–55)*
32 (9–55)*
41 (19–64)*
37 (10–65)*
o34w GA
34–36 6/7w GA o34w GA Percentage in which production of 4500 mL/ day ( = adequate milk supply) is reached (in percentage) n = 130
Difference between S-BPSP and I-BPSP group (95% CI)
Total
34–36 6/7w GA
Day post partum when production of 4500 mL/ day ( = adequate milk supply) is reached (in days) n = 95
Mean
34–36 6/7w GA o34w GA
(s.d. 1.0) (s.d. 0.5) (s.d. 2.6) (s.d. 0.6) (s.d. 2.1) (s.d. 0.8)
(s.d. 3.0) (s.d. 1.6) (s.d. 1.3) (s.d. 2.6) (s.d. 3.4) (s.d. 2.5)
Abbreviations: CI, confidence interval; I-BPSP, irregular breast pump suction pattern; S-BPSP, standard breast pump suction pattern. Significant bold values *Po0.05.
Time to secretory activation The I-BPSP group reached secretory activation (50 ml per day) significantly earlier than the S-BPSP group (P o0.001). Only in the preterm and late preterm group this difference remained significant after adjustment for gestational age (1.1 days later, 95% confidence interval (CI) 0.5 to 1.7 day, Table 2). Time to adequate milk production The I-BPSP group reached an adequate milk supply of more than 500 ml per day significantly earlier than the S-BPSP group (P o 0.01). After adjustment for gestational age, the difference between the two pumping groups remained significant (1.3 days, 95% CI 0.1 to 2.4 day; Table 2). Within 14 days, 74% of mothers had reached an adequate milk supply. Significantly more mothers who initiated with the I-BPSP (94%) compared with the S-BPSP group (53%; P o0.001) achieved an adequate milk supply. The significant difference in percentage reaching an adequate milk supply between the two pumping groups after adjustment for gestational age was in the group of term infants 42% (95% CI: 9 to 75%) and in the group of preterm infants o34w GA 37% (95% CI: 10 to 65%) and 34 to 36 6/7w GA 32% (95% CI: 9 to 55%) (Figure 2). In the S-BPSP group 56% (27/48) of the mothers with a preterm infant in the NICU reached an adequate milk supply © 2016 Nature America, Inc.
versus 29% (2/7) of the mothers with preterm infants not in the NICU, however, this was not significant (P = 0.236). Daily milk output Daily milk production was significantly higher in the I-BPSP group at each time point from day 3 till day 14, (P o 0.001, Figure 3), and the difference remained significant after adjustment for gestational age. A significantly higher milk production was also seen in preterm and late preterm infants at each time point and in term infants in the second week. DISCUSSION This study has confirmed that initiating lactation with the I-BPSP is superior to S-BPSP in pump-dependent mothers of both preterm, late preterm and term infants. This is the first study to examine the effectiveness of initiating lactation with the S-BPSP and the I-BPSP in preterm to term infants. Lactogenesis is triggered by withdrawal of progesterone after delivery of the placenta because placental progesterone inhibits prolactin-regulated milk synthesis. Thereafter, prolactin release by the anterior pituitary is directly related to the intensity of the suckling stimulus.16 Both immediate and persistent effects of Journal of Perinatology (2016), 47 – 51
Different breast pumping patterns; effects preterm to term EDM Post et al Adequate milk supply (%)
50 100 90 80 70 60 50 40 30 20 10 0
*
*
*
S-BPSP I-BPSP
