I would like to know whether exclusive breastfeeding is shown to be better than a combination of breast milk and formula, in developed countries.

The current advice of the World Health Organization (WHO) is that six months of exclusive breastfeeding leads to best health outcomes for the child. This means that the child is fed on demand, only with breast milk, for a full six months. Solid foods and liquids other than milk are not recommended.

I have seen this same recommendation on all the baby websites I've looked at (here is one example), and it has been repeated to me by a pediatrician, different nurses, and a lactation specialist, all in The Netherlands.

Formula-feeding (with no breast milk alongside it) leads to more hospitalizations for gastric and breathing problems.

However, there are two ways to non-exclusively breastfeed:

1) Introduce solid food before an infant is a full six months old. Evidence from the UK suggests that introducing solids earlier than six months has no adverse health outcomes. In fact, children who are exclusively breastfed are at a higher risk for iron deficiency.

2) Introduce formula alongside breast milk. This is the topic I am interested in.

I am looking for evidence that compares exclusive breastfeeding to half-breast milk, half-formula, in developed countries.

The WHO has to give recommendations that are not only simple and clear, but that pertain to the whole world. I am skeptical about how well this recommendation for exclusive breastfeeding translates into the wellbeing of children in developed countries. Is there evidence to support the WHO's recommendations?

  • 1
    One noted side effect of introducing formula through a bottle is that it apparently (citation needed) interferes with a baby's ability to learn to latch onto the breast, thus reducing the possibility of breast feeding. Feb 7, 2012 at 11:44
  • Good point, I forgot about that.
    – Ana
    Feb 7, 2012 at 19:43
  • This study is about PRETERM what about FULLTERM!?. Preterms are susceptible to these diseases and in need for intensive care.
    – user23225
    Dec 9, 2014 at 0:21

1 Answer 1


This prospective study in the UK found a serious risk of neonatal necrotising enterocolitis amongst formula-users.

In a prospective multicentre study on 926 preterm infants formally assigned to their early diet, necrotising enterocolitis developed in 51 (5·5%). Mortality was 26% in stringently confirmed cases. In exclusively formula-fed babies confirmed disease was 6-10 times more common than in those fed breast milk alone and 3 times more common than in those who received formula plus breast milk. Pasteurised donor milk seemed to be as protective as raw maternal milk.

I tried to read this report which looked at meta-analyses on breastfeeding research, which seemed very relevant, but was unable to confirm from it whether this stood up to further review.

Note: This only looks at one type of problem, and is not a measure of overall health outcomes of the child and mother. It also doesn't show causality.

  • Wait! Pure formula is 6-10 times worse than breast-feeding, and 3 times worse than a mixture of both. That is suggestive that a mixed approach is about twice as bad as breast feeding, BUT that difference, paradoxically, might not be statistically significant. Would need to see the paper's results to confirm.
    – Oddthinking
    Feb 7, 2012 at 20:43
  • 1
    Is there anything there that shows the effect on other infants (not preterm)?
    – Is Begot
    Dec 9, 2014 at 14:01

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