Interventions Designed to Promote Exclusive Breastfeeding in High-Income Countries: A Systematic Review Update

Information sources

Articles were obtained through a search of 11 databases: Academic Search Complete, CINAHL with full text, The Cochrane Library, Embase, Health Policy Reference Centre, Health Source Consumer Edition, Health Source-Nursing/Academic Edition, Maternity and Infant Care, MEDLINE with full text, Psychology and Behavioral Sciences Collection, and PsycINFO. The initial review searched for scholarly, peer-reviewed randomized trials published between January 2000 and June 2013. This review update searched from June 2013 to December 2016. The search terms used are the same as those used in the previous review, ²⁰ as shown in Figure 1, and resulted in a total of 924 abstracts that were reviewed for suitability by the second author. (An example of the search syntax can be found in Supplementary Table S1; Supplementary Data are available online at www.liebertpub.com/bfm).

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FIG. 1.

Search terms, as used in previous review.

Eligibility criteria and study selection

Articles were included if they were randomized controlled trials of interventions aimed at improving exclusive breastfeeding to 6 months. Articles were excluded if they were not published in English, had a follow-up period of less than 4 months postpartum, or referred specifically to developing or low-income countries. Other exclusion criteria were articles that were specific to adolescent mothers; those not aimed at increasing exclusive breastfeeding specifically; or those specific to breastfeeding in the presence of maternal smoking or a human immunodeficiency virus-positive status. Of the initial 924 abstracts revealed, 17 full-text articles were found to be relevant and were read in their entirety by the second and third authors. With unanimous agreement obtained by discussion, 5 articles were excluded, leaving 12 studies for the current review update (Supplementary Table S2 provides details of the excluded studies, with reasons) (Fig. 2).

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FIG. 2.

PRISMA systematic search record.

Data collection

Data, including authors and country, study's main aim, study's main outcomes, sample, design, exclusive breastfeeding definition, and theoretical basis, were extracted from articles and entered into Table 1.

Risk of bias

Risk of bias of individual studies was determined by a validity scoring system, modified from the Cochrane Collaboration tool for assessing risk of bias and used by Gardner et al. ²⁷ This system assesses and scores statistical power, intervention fidelity, blinding of outcome assessors, and intention-to-treat analysis. Scores were awarded on achievement of the required criteria. For statistical power, studies were allocated a score of 2 where power was met and a score of 0 where power analysis was not noted or statistical power was not met. Studies were given a score of 2 when an attempt to assess intervention fidelity was noted and a score of 0 when intervention fidelity was not noted. For blinding of outcome assessors, studies were awarded a score of 2 where assessors were blind to group allocations and a score of 0 where blinding was either not implemented or not mentioned in the design of the study. Finally, if no intention-to-treat analysis was used or this was unclear, studies were allocated a score of 0 and they were scored as 2 if it was applied. The mean risk of bias score for all included studies was assessed; scores could range from 0 to 8, with lower scores indicating a higher risk of bias.

Data analysis using the GRADE approach

The included studies were also assessed for their overall quality of evidence using the GRADE approach, ²⁶ as recommended by the Cochrane Handbook for Systematic Reviews of Interventions. ²⁸ The trials were evaluated for five factors that decrease the quality of evidence: limitations of the design, inconsistency, indirectness, imprecision, and publication bias. A further three factors that may increase the quality of the evidence were added: having a large magnitude of effect; plausible confounding variables; and dose–response gradient. An overall determination was then made about the quality of evidence. Randomized controlled trials have a high rating, and this is either downgraded or upgraded depending on the GRADE evaluation.

General description

Of the articles included in this review update (Table 1), five were conducted in the United States,^29–32 three in Hong Kong,^33–35 two in China,^36,37 and two in Australia.^38,39 Three studies stated that they were based on a theoretical underpinning, such as breastfeeding self-efficacy theory, ³³ motivational interviewing approach, ³⁸ and theory of planned behavior. ³⁶ Five of the 12 trials stated explicitly that they adopted the World Health Organization (WHO) definition ¹ of exclusive breastfeeding.^{30,35–37,39} All other articles defined exclusive breastfeeding in line with the WHO definition, apart from two articles, which did not give a definition of exclusive breastfeeding.^32,40 Ages of participants in these studies (where stated) ranged from 20 to 41 years with mean age of samples of between 27 and 31 years. The ethnicity of participants was diverse. Two samples were largely Hispanic or non-Hispanic black,^29,40 two were predominantly Hispanic,^30,31 three samples were Hong Kong Chinese,^33–35 two were Chinese,^36,37 two samples were ethnically diverse with English as a first language,^38,39 and one sample was ethnically diverse with English- and Spanish-speaking language groups. ³² Six studies had only primiparous samples,^33–37,40 four studies had both multiparous and primiparous samples,^29–32,38 and one study did not state the parity of the sample. ³⁹

Risk of bias

The average risk of bias across the 12 studies was 3.8 of a possible score of 8. This was slightly higher than the sample in the previous review ²⁰ where the average was 2.8. One study achieved the maximum score of 8, ²⁹ two studies received scores of 6,^33,38 six studies received scores of 4,^{30–32,34,35,40} one study scored 2, ³⁶ and two studies scored 0.^37,39

Intervention components

Details of the intervention methodologies (time of delivery, prenatal/postnatal, delivery by hospital staff and/or lactation experts, peer support, telephone support, face-to-face support, number of intervention sessions/duration of intervention, follow-up time points, and findings in relation to the success of interventions for any breastfeeding and for exclusive breastfeeding) are presented in Supplementary Table S3.

Interventions utilized in the articles in this update review focused on support and education in the following time periods: (1) pregnancy,^29,35 (2) during the hospital stay, ³⁴ (3) postpartum,^34,38,39 (4) during hospital stay and postpartum,^36,40 and (5) pregnancy and postpartum.^{29,31–33,37} Interventions implemented in the prenatal visit focused on maternal education, through hospital staff, face-to-face,^29,33,35 by peer counsellors, ³² by lactation educators (trained undergraduate students), by phone call, ³¹ and by text messages. ³⁷ Interventions delivered during hospital stays focused on one-on-one support for breastfeeding by hospital staff^34,36 and education during hospital stay. ⁴⁰ Most of the postnatal interventions involved regular phone calls.^{29,31,33,34,36,40} Other postnatal interventions included access to an internet site, ³⁹ regular text messages, ³⁷ and face-to-face discussions with mothers during the infant's immunization sessions. ³⁸

Effect of interventions on initiation/duration of exclusive breastfeeding

Of the 12 studies in this review update, the interventions conducted in 8 of the studies did not have a significant improvement in exclusive breastfeeding rates in the 4–6-month time period.^{29,30,32–35,38,40} All of these eight articles measured exclusive breastfeeding at 6 months (not at 4 or 5 months), and four had very low numbers overall of infants being exclusively breastfed at the 6-month time point.^29,30,33,40 Four articles found significant differences from study interventions.^31,36,37,39 Three of these articles measured exclusive breastfeeding at both 4 and 6 months^36,37,39 and one only at 6 months. ³¹

Successful interventions

All of the four successful interventions featured postpartum support or education for mothers through some sort of technology in the postpartum period, including telephone calls,^31,36 text messaging, ³⁷ and website access. ³⁹ Telephone calls were a one-on-one intervention, while text messaging and website access had generalized content. The website also included a chat site and e-mail access to a lactation consultant. The postpartum sections of the interventions were over a relatively long period; two interventions continued to 6 months^36,39 and 1–12 months, ³⁷ and one had 17 follow-up phone calls. ³¹

Two of the successful interventions began in the prenatal period with phone calls ³¹ and texts, ³⁷ while one of the successful interventions began during the hospital stay with one-on-one support every day of hospital stay plus an information session at the hospital. ³⁶ One successful intervention was only conducted in the postpartum period. ³⁹ The two studies that utilized telephone calls in the postpartum period had the highest percentage increase in proportion of mothers still exclusively breastfeeding,^31,36 as indicted in Table 2, although one of these studies was only marginally significant. ³¹ The combination of education and support appeared to be particularly successful in the study with the largest effect sizes, where there were percentage increases in exclusive breastfeeding of 41% and 32% at 4 and 6 months, respectively. ³⁶

Unsuccessful interventions

Of the eight unsuccessful interventions, one involved a single prenatal workshop ³⁵ and one involved three breastfeeding support sessions delivered during the first 2 days of the hospital visit ^{34 (Intervention 1)}. Five of the unsuccessful interventions employed telephone calls during the postpartum period; however, they were for shorter periods than the successful interventions: 2 weeks,^32,33,40 3 months, ²⁹ or 4 months^{32,34 (Intervention 2)}. The fifth unsuccessful intervention involved one-on-one care from clinic staff for three sessions between 2 and 6 months postpartum, during visits for infant vaccinations. ³⁸ It is possible that the timing of the intervention (while babies were being vaccinated) was not conducive to discussing breastfeeding with mothers.

The final unsuccessful intervention was aimed at improving exclusive breastfeeding for overweight and obese women. ³⁰ This was a highly intensive intervention, involving 3 prenatal visits, in-hospital support, and up to 11 postpartum visits. The authors state that the results of this randomized control trial and previous research suggest that barriers faced by overweight and obese women have not yet been fully understood.

Intervention control and fidelity

Detailed information regarding study power, intervention fidelity, definitions of usual care, stratification, consideration of maternal body–mass index, and intention-to-treat analysis is provided in Supplementary Table S4. Of the 12 included studies, 3 did not note power calculations^37,39,40 and 2 further studies had calculated power, but were underpowered due to a loss of sample at follow-up.^30,31 Intervention fidelity of the administration of the intervention program was not noted in six studies.^{30,32,33,37,39,40} Only two studies reported maternal body–mass index,^29,30 a risk factor known to impact breastfeeding rates.^41–43

GRADE quality rating of evidence

As in the previous review, ²⁰ all the studies included in this review update were randomized controlled trials and thus have potential for there being a high quality of evidence. The inconsistent results produced by these studies as well as the limitations in design (such as lack of power and lack of intervention fidelity) suggest that the quality of evidence for breastfeeding interventions and exclusive breastfeeding outcomes is moderate, according to GRADE guidelines, ²⁶ but higher than the previous review, where there were more issues associated with breastfeeding definitions and definitions of usual care. ²⁰ More detail on GRADE evidence is contained in Supplementary Table S5.

What are the limitations of current approaches to exclusive breastfeeding promotion?

In the previous review, several limitations to current approaches to the promotion of exclusive breastfeeding were identified. ²⁰ These limitations included lack of power, inconsistent (or lack of) definitions of usual care, insufficient information on assessment of the intervention implementation when there were several research team members involved, and insufficient reporting of maternal body–mass index. In this review update, studies that lacked power calculations, or were unable to fulfill power requirements, remained a methodological flaw. Participant numbers were insufficient in several studies to detect a change if it existed, and this could be a partial explanation for the lack of evidence of effectiveness of some of the interventions. Of the three studies with clustered data, two studies adjusted analyses to account for this,^34,38 while a further study did not appear to have made adjustments for clustering. ³⁷ Maternal body–mass index was not stated in most studies included in this review update.

Definitions of usual care were clearer in the review update studies than the studies in the previous review. ²⁰ Definitions of usual care were not stated in 1 article, ⁴⁰ and insufficient in a 2nd article ³⁷ ; however, the other 10 articles had sufficiently detailed information on this aspect. In studies where usual care is highly supportive, the sample size to detect a statistical difference would need to be increased. The control group in the article for the overweight/obese sample had more comprehensive breastfeeding support for the control sample than would usually be available, which may have contributed to the lack of statistical difference. ³⁰

Where data were available at both 4 and 6 months, effect sizes in the successful articles were generally higher at 4 months,^36,39 except for one article. ³⁷ Given that mothers are routinely recommended to introduce solid food at, or by, 6 months, ⁴⁵ measuring exclusive breastfeeding at this point can be challenging. The introduction of solid foods at 6 months may lower the ability of some of the studies to find an effect at this time point, even when the intervention had been successful earlier in the postpartum period. Where this was the case, and there were no data presented at 4 or 5 months, the possible success of the intervention may not be apparent.

Future research

The successful studies in this review update featured lengthy education or support in the home environment in the postpartum period, through telephone, text messaging, or website access. Overall, the use of telephone support produced higher effect sizes than the other technologies, possibly due to the one-to-one support supplied in this type of intervention. Text messaging and website access (with chat platform) were also effective and are highly cost-effective initiatives that deserve further investigation and refinement. Finding effective interventions to increase exclusive breastfeeding for women who are overweight or obese is an important next step in improving exclusive breastfeeding rates. ⁴⁶ The low outcomes from the intensive intervention featured in the study by Chapman et al. ³⁰ suggest that this is an area that is still insufficiently understood.