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Table 4 Impact of expressing on breastfeeding outcomes

From: Prevalence and outcomes of breast milk expressing in women with healthy term infants: a systematic review

Author, year, country Design Location, participants, year of study and recruitment Study aims and outcome measures Results Strengths/Limitations
Chapman et al. 2001 USA [45] RCT Hartford, Connecticut Effects of expressing before the onset of lactation : - No significant difference in milk transfer or breastfeeding duration between women who expressed breast milk and those who did not. Only women who had a caesarean section
n = 60 - on early milk transfer - Primiparous women in pumping group breastfed for 5 months less than those in control group but this finding was not statistically significant. Study underpowered for primiparous women
1997–1998 - on subsequent breastfeeding duration   
Convenience sample 8–24 hours post Caesarean Section    
Schwartz et al. 2002 USA [42] Prospective cohort Detroit, Ann Arbor and Southfield, Michigan and Omaha, Nebraska - Determine demographic, behavioural and clinical factors associated with weaning from breast in the first 12 weeks - Michigan women (n = 711) who expressed breast milk were 3 times more likely to wean than those who didn’t (Hazard Ratio: 3.0 95% CI 1.3,6.7) Large study
n = 946   - Nebraska women (n = 235) showed no association between pumping and weaning (HR: 0.6, 95% CI 0.3,1.5) Only measured to 12 weeks
1994–1998    Non-representative sample
Recruitment:    Michigan group were recruited from an alternative birthing centre and were significantly more likely to be older than 30 years, have a bachelor’s degree, have 3 or more children and have had a vaginal birth
Michigan - at birth centre orientation    
Nebraska - on maternity leave application to large company    
Ortiz 2004 USA [37] Clinical audit Burbank, California - Duration of breast milk feeding related to a range of employee chosen lactation support options - 98% (452/ 462) breastfeeding initiation Large study over 4.5 years
n = 462 - 74% (246/332) expressed milk until infant at least 6 months Limited differentiation between breastfeeding and expressing / breast milk feeding
1993–1999 - 24% (81/332) expressed milk until infant at least 12 months No information re any other infant feeding/exclusivity of breast milk feeding
Antenatal recruitment in workplace - Mean age of infants at maternal cessation of pumping at work 6.3 months No consideration of options in the workplace to breastfeed at the breast
Geraghty et al. 2005 USA [1] Retrospective cohort Cincinnati, Ohio Measure breast pump use Of breast milk feeding mothers: Large sample size
n = 346 Identify relationships between breast pump use and: - 10% (24/346) breastfed exclusively for a minimum of 6 months Breastfeeding / breast milk feeding clearly differentiated
2002 - singleton vs. multiple pregnancy - 16% (55/346) breastfed exclusively for duration of their breast milk feeding Periodic reports re. proportion of expressing versus breastfeeding (at 1 day, 3 days, 2 weeks and monthly until 6 months)
Random selection Postal recruitment when infants were between 2 and 3 years old - gestation at birth - 77% (182/236) expressed at some time in first 6 months Retrospective data, possible recall bias as participants were recruited 2 or more years post birth
  - breastfeeding outcomes - 59% (140/236 ) ceased breast milk feeding by 6 months  
   Of the 140 women who had ceased breast milk feeding by 6 months, at the time point just prior to exclusive formula feeding:  
   - 76% (106/140) were either expressing exclusively or combining expressing with breastfeeding  
   - 24% (34/140) were breastfeeding  
   Early breastfeeding associated with a longer duration of breast milk feeding  
Win et al. 2006 Australia [55] Prospective cohort Perth, Western Australia - Investigate association between breast milk expression and breastfeeding duration - Mothers who expressed at least once more likely to be breastfeeding at 6 months (RR: 0.71, 95% CI 0.52,0.98) Prospective design assisting recall
PIFS II    Ever “expressed” / “any” breastfeeding
n = 587    ? lower socio economic bias
2002–03    No account of frequency of expressing
Recruited in hospital at birth.    
Meehan et al. 2008 USA [43] Quasi-experimental Los Angeles, California - Evaluation of program to facilitate breastfeeding for low income mothers - Electric pump loan associated with more breastfeeding at 6 months. Mothers loaned a breast pump 5.5 times more likely to than those who hadn’t received one to not have requested formula by 6 months Limited reliability of proxy measurement to assess breast milk feeding prevalence or duration
n = 208 - Maternal request for formula from WIC program used as proxy measurement to give indication of partial breastfeeding (OR: 5.5, 95% CI 2.0,15.1) No differentiation between breastfeeding and breast milk feeding
Breast pump loan program for low income Women with Children (WIC) recipients    
Fein 2008 USA [41] Prospective cohort National - Examine strategies used to combine work and breastfeeding Median duration of breast milk feeding associated with workplace practices: Large National study
n = 810 - Identify strategies associated with enhanced breastfeeding intensity/longer duration   Prospective design
2005–2007   - expressing and breastfeeding (32.4 weeks) (n = 75) Questionnaire design with 7 day recall
from IFPS II   - breastfeed at the breast only (31.4 weeks) (n = 250) No description of feeding method away from workplace
Recruitment via postal questionnaire in late pregnancy   - expressing only (26.3 weeks) (n = 75) Older, less educated, low income and women from racial/ethnic minority groups underrepresented
   - neither breastfeeding or expressing (14.3 weeks) (n = 128)  
Clemons & Amir 2010 Australia [5] Cross-sectional State-wide, Victoria - Prevalence of breast milk expression - 27% (218/903) indicated that expressing had allowed them to breastfeed for longer Large study
n = 903 - Demographic characteristics of women who express, why and how they do it   Possible selection bias (members of ABA)
2008 - Women’s experience of using breast pumps   Timing of questionnaire, possible recall bias
online questionnaire    
ABA members with internet addresses    
Dabritz et al. 2010 USA [56] Retrospective cohort Yolo County, California - Assess relationship between maternal experience in hospital and any breastfeeding at six months - Almost exclusive breastfeeding at 6 months associated with not using a breast pump in hospital 77% (93/121) compared to 21% (25/121) who did use a pump in hospital (OR: 0.6 95% CI 0.3,1.0) Differentiation between breastfeeding and breast milk feeding unclear
n = 382    
2006–07    Possible recall bias - interviews 6–9 months after birth
Recruited in community after birth - 8 months    
Hornbeak et al. 2010 Singapore [6] Retrospective cohort Singapore - Record prevalence and patterns of breastfeeding in Singaporean Chinese mothers - Breast milk feeding initiation and duration increased over time and were independently associated with higher maternal education, increased milk expression and complementary feeding Large representative sample of Chinese Singaporean mothers
n = 3009   Changes between 2000–01 and 2006–08: Possible recall bias - recruitment 6–72 months after birth
2006–2008   Infant formula feeding 31% (66/210) to 18% (118/656) Gestational age not indicated
Recruited mothers of 6–72 month Chinese Singaporean children through STARS   Breast milk feed initiation 69% (144/210) to 82% (538/656)  
Mailed invitation   Expressed breast milk 9% (18/210) to 18% (118/656)  
   Combination feeding 26% (54/210) to 41% (269/656)  
Geraghty et al. 2012 USA [29] Prospective cohort Cincinnati, Ohio - Determine who expresses their milk by end of 4 weeks and how long they continue feeding - Milk expression common in first month postpartum Prospective design
n = 60   - Milk expression by 4 weeks did not significantly influence duration of breast milk feeding Clear differentiation between breastfeeding and breast milk feeding
2004–2007    Recruitment of women who planned to breastfeed for 6 months or more
Participants enrolled in a research human milk bank recruited at home in first week postpartum    Mothers recruited for study knew they were going to be assisted to pump and may have been more likely to be comfortable with this.
      Possible introduction of bias as weekly collection of breast milk was initiated at 1 week by research nurse using an electric breast pump