Breastfeeding and Outcome

February 22, 2016


Special Issue: Impact of breastfeeding on maternal and child health. Grummer-Strawn LM and Rollins N, Guest Editors. Acta Paediatrica Dec 2015, volume 104: supplement 467, pp 1-134.


Mikael Norman
MD, PhD, professor
Department of Neonatal Medicine, H1:02
Karolinska Institutet & University Hospital


Systematic review


What are the health effects of breastfeeding?


  • Design: Multiple systematic reviews (10) of the literature, meta-analyses and GRADE profiling of the evidence. Studies could be included of varying designs, from observational data (cohort and case-control studies) to randomized controlled trials (usually secondary analyses). Most of the literature was based on cross-sectional retrospective cohort studies with the potential risk of confounded interpretation.
  • Allocation: N/A
  • Blinding: Each individual review had at least two reviewers, who searched the literature according to a predefined strategy. Relevant articles for each outcome were independently assessed using predefined inclusion criteria and data were extracted.
  • Follow-up period: varying from infancy to adulthood
  • Setting: data from different developed and developing countries (low, middle and high income countries).
  • Patients: N/A (healthy infants)
  • Intervention/exposure: Any breastfeeding, which therefore included exposures of varying duration, intensity and modes of delivering breast milk. Commonly, exclusive breastfeeding for a defined period of time was compared with partial or non-breastfeeding.
  • Outcomes: Infant and child mortality, cognition, child growth, long-term outcomes as metabolic and cardiovascular risk factors, overweight and obesity, asthma and allergies, malocclusion, dental caries, otitis media in childhood, and maternal health outcomes.
  • Sample Sizes:
  • Patient follow-up: varying from months to >20 years
  • Funding: This supplement was coordinated by World Health Organization with financial support from the Bill & Melinda Gates Foundation.


Primary outcome in review Key note


Quality of evidence

(GRADE profile);

other comments

Number of studies in meta-analyses

/sample sizes

Mortality (infant & child)10 BF protective (all cause and infection-related) Low-very low grade evidence (but critical importance) 13 studies;

total sample size N=46499 infants

Intelligence, schooling6 BF associated with

improved performance

Pooled effect estimate of BF:

+3.4 (95%CI 2.3;4.6) IQ-points (adjusted for maternal IQ)

17 studies; 11 studies ≥500 participants
Infant & child growth5 Inconclusive evidence Heterogeneity among studies 35 studies (16 RCTs, 4 deemed as high-quality)
Overweight & obesity7 BF protective Observational data but finding stable in large size studies with control of confounding:

aOR: 0.87 (95%CI 0.81; 0.94)

105 studies

(11 judged as high- quality)

Type 2 diabetes7 BF protective Pooled effect:

OR: 0.65 (95%CI 0.49;0.86)

11 studies
Blood pressure and cholesterol7 Not associated with BF Marked heterogeneity for

blood pressure studies

43 studies on BP/ 46 studies on chol.
Asthma8 BF (longer duration) protective Low grade evidence 42 studies, sample size 5900 – 391000
Allergic rhinitis and eczema8 BF protective (eczema ≤2 yrs and allergic rhinitis ≤5 yrs) Low-very low grade evidence 16 on rhinitis/

42 on eczema

Food allergy8 Not associated with BF 13 studies
Malocclusion9 BF (both exclusive and prolonged) protective OR: 0.34 (95%CI 0.24;0.48) 41 studies
Dental caries12 BF (up to 12 months)


Increased risk of caries in children BF >12 months may be due to confounding 63 studies
Otitis media3 BF protective up to

2 years-of-age

(but thereafter no continued benefit)

Exclusive BF for 6 months associated with 43% reduction in otitis during the first 2 yrs 24 studies
Maternal breast and ovarian carcinoma, type 2 diabetes4 BF protective 163 articles
Interventions to improve BF11 Interventions should be delivered in a

combination of settings

(health systems, home, community)

Baby friendly hospital support most effective 195 articles


The editorial provided by the two guest editors Laurence M. Grummer-Strawn and Nigel Rollins high-lighted five key messages from these analyses: 1) health benefits of breastfeeding are substantial, many of these benefits are experienced well beyond the period of breast feeding, 2) it is critical to examine the breadth of the literature on an outcome whereas a single study claiming beneficial (or non-beneficial) effects is insufficient, 3) the mechanisms by which breastfeeding affect health are extremely varied, 4) many of the articles forming the base for meta-analyses suffered from methodological weaknesses that limit conclusions, and 5) breastfeeding practices are responsive to interventions delivered in health care systems, communities and homes.

Visit Acta to access a pdf copy of this EBNEO commentary!


This supplement provides a picture of different health effects of breastfeeding. It extends and updates data from a previous WHO report (1). The major strengths include systematic search strategies and clinically relevant outcomes. As pointed out by the authors and in the editorial (2) limitations are related to methodological weaknesses of the studies included in the reviews. Nevertheless, the ten reviews providing in total 889 references represent the so far largest and best source of knowledge on this topic (3-12).The authors should therefore receive plaudit for their joint and huge effort.

The mechanisms by which breastfeeding may affect outcome are diverse. Breastmilk is not only a nutrient (with varying content and composition between lactating mothers and within the same woman over time), it contains cells, immune factors, microbes, hormones and growth factors. The intensity and duration of breastfeeding, and the delivery method of breastmilk (feeding from the breast, tube or bottle) are also added to the equation. While immune factors may be important for later risk of infections, eczema and allergy, the delivery method – breastfeeding (were for example the infant can regulate the amount of milk) or bottle – may have implications for later risk of obesity.

In a disclaimer, the guest editors state that the views expressed by the authors of the individual articles do not necessarily represent the policies of the WHO (known for its commitment to protect, promote and support breastfeeding). While breastfeeding is generally recommended, the evidence for doing was mostly found to be poor. Flaws in study designs, different types of bias, overt risks of confounding (for example by maternal IQ and weight) and unclear or varying definitions of breastfeeding were common. In this context, the use of GRADE may be helpful (13). GRADE aims not only to weigh quality of evidence, but also provide a recommendation. While the quality of evidence was low in most of the reviews on breastfeeding effects, the recommendation to breastfeed stayed firm. The GRADE recommendation not only reflects the extent to which we can be confident that breastfeeding reduce morbidity and mortality, but also the extent to which breastfeeding outweigh undesirable consequences of other alternatives (with impact on morbidity, mortality, quality of life and use of resources).

Why is this knowledge important to neonatologists? Mainly, because we are counseling mothers. With expectations of being an expert acting in the best interest of the baby, our role is to provide and discuss the benefits of breastfeeding. This information and knowledge cannot be delegated to lactation consultants, mid-wives and nurses alone, but doctors need to actively engage as well.

Globally, only 38% of infants are exclusively breastfed and it is estimated that suboptimal breastfeeding contributes to 800,000 infant annual deaths. The goal set for 2025, is to increase the rate of exclusive breastfeeding to at least 50% in the first six months (14). In the context of breastfeeding promotion, the data and knowledge presented in the present supplement referred to herein are central.


  1. Horta BL, Victora CG. Long-term effects of breastfeeding: A systematic review. WHO Press 2013. Available from: URL:
  2. Grummer-Strawn LM, Rollins N. Summarising the health effects of breastfeeding. Acta Paediatr 2015; 104:1-2.
  3. Bowatte G, Tham R, Allen KJ, Tan DJ, Lau M, Dai X, et al. Breastfeeding and childhood acute otitis media: a systematic review and meta-analysis. Acta Paediatr 2015; 104:85-95.
  4. Chowdhury R, Sinha B, Sankar MJ, Taneja S, Bhandari N, Rollins N, et al. Breastfeeding and maternal health outcomes: a systematic review and meta-analysis. Acta Paediatr 2015; 104:96-113.
  5. Giugliani ER, Horta BL, Loret de Mola C, Lisboa BO, Victora CG. Effect of breastfeeding promotion interventions on child growth: a systematic review and meta-analysis. Acta Paediatr 2015; 104:20-9.
  6. Horta BL, Loret de Mola C, Victora CG. Breastfeeding and intelligence: a systematic review and meta-analysis. Acta Paediatr 2015; 104:14-9.
  7. Horta BL, Loret de Mola C, Victora CG. Long-term consequences of breastfeeding on cholesterol, obesity, systolic blood pressure and type 2 diabetes: a systematic review and meta-analysis. Acta Paediatr 2015; 104:30-7.
  8. Lodge CJ, Tan DJ, Lau MX, Dai X, Tham R, Lowe AJ, et al. Breastfeeding and asthma and allergies: a systematic review and meta-analysis. Acta Paediatr 2015; 104:38-53.
  9. Peres KG, Cascaes AM, Nascimento GG, Victora CG. Effect of breastfeeding on malocclusions: a systematic review and meta-analysis. Acta Paediatr 2015; 104:54-61.
  10. Sankar MJ, Sinha B, Chowdhury R, Bhandari N, Taneja S, Martines J, et al. Optimal breastfeeding practices and infant and child mortality: a systematic review and meta-analysis. Acta Paediatr 2015; 104: 3-13.
  11. Sinha B, Chowdhury R, Sankar MJ, Martines J, Taneja S, Mazumder S, et al. Interventions to improve breastfeeding outcomes: a systematic review and meta-analysis. Acta Paediatr 2015; 104:114-34.
  12. Tham R, Bowatte G, Dharmage SC, Tan DJ, Lau MX, Dai X, et al. Breastfeeding and the risk of dental caries: a systematic review and meta-analysis. Acta Paediatr 2015; 104:62-84.
  13. Guyatt GH, Oxman AD, Kunz R, Falck-Ytter Y, Vist GE, Liberati A, et al. Going from evidence to recommendations. BMJ 2008; 336:1049-51.
  14. World Health Organization Global Targets 2025. Available from: URL: