Data Sources:
We searched the MEDLINE, PsycINFO, Cochrane, and CINAHL databases through June 3, 2024. We supplemented searches by examining reference lists from related articles and searched federal trial registries for ongoing trials. We conducted ongoing surveillance for relevant literature through January 22, 2025.
Study Selection:
Two researchers reviewed 3,720 titles and abstracts and 290 full-text articles for inclusion. We included randomized clinical trials (RCTs) evaluating interventions to support breastfeeding that were initiated in, feasible for, or referable from primary care settings. Interventions could take place during prenatal, peripartum, or postpartum time periods and included interventions provided by professionals, lay persons, or through digital modes of delivery. We did not include policy evaluations or health system-level interventions. Studies had to report infant or maternal health outcomes, the prevalence of breastfeeding or breastfeeding duration, or harms. We conducted dual, independent critical appraisal of all provisionally included studies and abstracted all important study details and results from all studies rated fair or good quality. Data was abstracted by one reviewer and confirmed by another.
Data Analysis:
We narratively synthesized results for health outcomes and harms. For breastfeeding outcomes, we conducted random effects meta-analysis and calculated pooled risk ratios (RRs) for any and exclusive breastfeeding initiation and at postpartum time points of less than 3 months, 3 months to less than 6 months, and 6 months. We explored potential effect modification by various population and intervention characteristics and generated funnel plots and conducted tests for small-study effects for all pooled analyses.
Results:
We included 90 RCTs reported in 125 publications. Thirty-seven studies were identified in this update and 53 were carried forward from the previous review. Most studies recruited participants during pregnancy or shortly following delivery. Trials taking place in the United States predominately represented low-income Hispanic or Latina and Black women. Most interventions provided breastfeeding education and support by a professional such as a nurse, midwife, or lactation consultant or trained peer interventionist. Most interventions took place over six sessions or fewer and were variable in terms of their timing (prenatal, peripartum, and/or postpartum).
Infant and maternal health outcomes. There was mixed evidence on the effectiveness of breastfeeding support interventions on infant health outcomes from 10 trials (n=6,592), including gastrointestinal outcomes, otitis media, the number of healthcare visits for respiratory tract illnesses, and rates of general infant healthcare utilization. In all cases, more favorable effects were seen on these outcomes among infants born to intervention versus control group parents, but very few reported these differences to be statistically significant. For maternal health outcomes, nine trials (n=2,334) reported maternal symptoms of anxiety, depression, or well-being at up to 3 months postpartum. Most of the studies reported better symptom scores among intervention mothers versus control mothers; however, none of the differences between groups were statistically different.
Breastfeeding outcomes. Breastfeeding support interventions were associated with higher rates of any and exclusive breastfeeding at less than 3 months, 3 months to less than 6 months, and at 6 months. For example, at 6 months, the likelihood of any breastfeeding and exclusive breastfeeding was 13 percent (RR, 1.13 [95% CI, 1.05 to 1.22]; k=37; n=13,579) and 46 percent higher (RR, 1.46 [95% CI, 1.20 to 1.78]; k=37; n=14,398]), respectively. The median differences in absolute rates of breastfeeding between groups ranged from 1.3 to 7.1 percentage points at various time points for any and exclusive breastfeeding, with slightly larger effects for exclusive versus any breastfeeding. There was no consistent evidence that the results varied by any prespecified population or intervention characteristics.
Harms. Potential harms related to breastfeeding support interventions were minimally reported (7 trials, n=1,404) and indicated no harm related to the interventions. There was no evidence of differences in rates of breastfeeding problems between those in the intervention versus usual care groups.
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