Tag Archives: Breastfeeding

Breastfeeding and SIDS

Over the years many studies have shown an association between breastfeeding and decreased risk of sudden infant death syndrome (SIDS), with a previous meta-analysis showing an adjusted odds ratio of 0.55 (95% CI 0.44-0.69), which increased to 0.27 (95% CI 0.24-0.31) with exclusive breastfeeding.[1] However, it has been difficult to identify just how long breastfeeding needs to continue to realise this benefit. This is because duration of breastfeeding has not been correlated with reduction in risk. As a follow-up to their original meta-analysis, Thompson and colleagues worked in cooperation with the authors of the included studies to obtain individual-level data.[2] They were able to glean information on duration of breastfeeding so that the association between duration and effect could be examined. In total 9,104 infants were analysed from eight case-control studies. Although analysis showed some protection against SIDS associated with any breastfeeding up to 2 months, this was not statistically significant after controlling for potential confounders. When confounders were controlled for, analysis found that any breastfeeding for at least 2 months, compared to no breastfeeding, had an adjusted odds ratio (aOR) of 0.60 (95% CI 0.44-0.82), while it was a similar aOR of 0.61 (95% CI 0.42-0.87) for exclusive breastfeeding. The aOR for any amount of breastfeeding compared to none improved with increased duration – an aOR of 0.40 (95% CI 0.26-0.63) with 4-6 months breastfeeding, and 0.36 (95% CI 0.22-0.61) with at least 6 months breastfeeding. A similar improvement was seen with at least 4 months of exclusive breastfeeding (aOR 0.46, 95% CI 0.29-0.74).

In order to lower the incidence of SIDS it is important that new mothers are encouraged to breastfeed and to continue for at least 2 months, even if they are unable to do so exclusively, as any amount of breastfeeding seems to confer more protection than none.

— Peter Chilton, Research Fellow


  1. Hauck FR, Thompson JM, Tanabe KO, Moon RY, Vennemann MM. Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis. Pediatrics. 2011; 128(1): 103–10
  2. Thompson JMD, Tanabe K, Moon RY, Mitchell EA, McGarvey C, Tappin D, Blair PS, Hauck FR. Duration of Breastfeeding and Risk of SIDS: An Individual Participant Data Meta-analysis. Pediatrics. 2017: e20171324.

Crying Infants – the Epidemiology of ‘Colic’

The period following childbirth is stressful for parents and uncontrollable crying is an important cause of this stress. Wolke and colleagues [1] have consolidated the results of studies across the world in a meta-analysis and show that:

  1. Crying peaks at around six weeks of age, and then declines sharply over the next three months.
  2. Bottle or mixed-fed babies cry less than those that are purely breastfed.
  3. Crying is much more common in some countries (Canada and UK) than others (Denmark and Japan), and this is a robust finding (i.e. replicated across many studies). I don’t suppose that this is the result of lower breastfeeding rates in Denmark and Japan than in Canada or the UK?

What the study does not show is how crying varies within families or by birth order. Nor does there seem to be an effective remedy for the problem. Pilgrim was right, it is not easy being a human, not at the beginning, not in the middle, and certainly not at the end.

— Richard Lilford, CLAHRC WM Director


  1. Wolke D, Bilgin A, Samara M. Systematic Review and Meta-Analysis: Fussing and Crying Durations and Prevalence of Colic in Infants. J Pediatr. 2017.


Cluster Trial of Home Visits for Newborn Children in Sub-Saharan Africa

Forty percent of childhood deaths in low- and middle-income countries (LMICs) take place within the first month after birth. Trials conducted in Asia have shown that an intervention whereby home-visits are made over this crucial period of life is effective. Would it work in Africa? To find out, Betty Kirkwood and colleagues randomised 197 clusters in Ghana to intervention and control.[1] Mothers in the intervention clusters were to receive two home visits in pregnancy and three in the first week after birth. Coverage was good and the proportion of mothers who adopted health promoting behaviours increased. These behaviours included use of anti-mosquito bed-nets, timely transfer to a facility when appropriate, breastfeeding, ‘kangaroo’ care, delayed bathing of the baby, and hand-washing. Reductions in neonatal mortality observed in this trial alone were not significant, but a significant 12% reduction in mortality was estimated when the data were combined with those from the Asian trials in a meta-analysis. The CLAHRC WM Director could not find out whether the study was rural or urban. Trials of women’s groups [2] provide positive results in rural areas but not slums. It would be interesting to examine the effect of place of residence further since half of all African people will soon be urban, and more than half of those people will live in slums.

— Richard Lilford, CLAHRC WM Director


  1. Kirkwood BR, Manu A, ten Asbroek AHA, et al. Effect of the Newhints home-visits intervention on neonatal mortality rate and care practices in Ghana: a cluster randomised controlled trial. Lancet. 2013; 381(9884): 2184-92.
  2. Prost A, Colbourn T, Seward N, et al. Women’s groups practising participatory learning and action to improve maternal and newborn health in resource-limited settings: systematic review and meta-analysis. Lancet. 2013; 381(9879): 1736-46.


Does Breastfeeding Protect Against Type 2 Diabetes in Women Who Have Had Gestational Diabetes?

Pregnancy is a kind of metabolic stress test for risk of diabetes later in life; the life time risk of type 2 diabetes mellitus is a whopping seven-fold increase above controls in women with gestational diabetes. Breast feeding has positive metabolic effects and promotes weight loss. It is therefore highly plausible that breastfeeding would reduce the risk of type 2 diabetes in women whose pregnancies were complicated by gestational diabetes. However, there have been surprisingly few studies of this hypothesis, and those that have been done have mostly been retrospective and did not collect enough information to adjust for all known confounders. The small number of prospective studies have been too few to examine for risk-adjusted associations between exposure and outcome. This deficiency in the literature has now been corrected by a mighty study of 1000 women with gestational diabetes, intensively investigated at base line, and followed-up for two years after delivery.[1] The results, after extensive adjustment, are clear. Breastfeeding is associated with a large decrease (approximately 50%) in incidence of diabetes over follow-up, and there is a strong positive association between duration of breastfeeding and degree of protection.

— Richard Lilford, CLAHRC WM Director


  1. Gunderson EP, Hurston SR, Ning X, et al. Lactation and Progression to Type 2 Diabetes Mellitus After Gestational Diabetes Mellitus. Ann Intern Med. 2015; 163: 889-98.

Another Day, Another (Badly-Reported) Health Story in the Media…

Recent health issues reported in the British media have included the link between consumption of red and processed meat with an increased risk of cancer and the need for a ‘sugar tax’ to curb the ever-increasing rates of obesity and its associated health problems. These are big, newsworthy issues relating to the effect of diet and lifestyle on health: the World Cancer Research Fund estimate that around 6,000 cases of bowel cancer in the UK could be prevented by reducing consumption of red and processed meat,[1] while a 20p/litre tax on sugar-sweetened beverages could reduce the number of obese adults in the UK by 180,000 according to the Faculty of Public Health.[2]

So one has to feel a little pity for a journalist tasked with writing a piece about a study investigating whether the composition of a mother’s breast milk was associated with infant weight and body composition.[3] The journalist from The Times seemed to approach this task by jumping on the obesity bandwagon; two key quotes from the story are: “A mother’s milk can increase the chance of a child growing up obese” and “A study … identified sugars in breastmilk that heightened a baby’s risk of being overweight by the age of 6 months”. This seemed to fly in the face of almost everything I had ever read about breastfeeding, so I decided to look at the evidence in a bit more detail.

The paper was based on a sample of 25 breastfeeding mothers and their babies. No babies were formula-fed. Outcomes were infant growth (weight and length) and body composition (percentage fat, total fat and lean mass). Whether or not the baby was ‘overweight’ or ‘obese’ was not an outcome. An association between the level of different human milk oligosaccharides (HMOs) in breast milk and infant weight and body composition was identified by the study authors, adding to the evidence base regarding the factors influencing a baby’s growth and development. The authors themselves made no direct claim that breastfeeding causes childhood obesity (three separate meta-analyses have, in fact, shown the opposite [4-6]), with the smallest of these studies including data for almost 30,000 babies.

The journalist’s train of thought may have gone thus:

44 GB Health Story in Media Fig 1

The first step in this chain was identified by the study authors. But was the journalist justified in making the second?

The increase in risk of adulthood obesity given a high weight-for-age percentile in infancy has been known for some time,[7] so the second link is plausible. But can it automatically be inferred from this study? To do so relies on the increases in body fat/fat mass being of such magnitude to class some of the infants in this study as overweight or obese at six months and we simply don’t know if this was the case. Instead, it could be possible that babies receiving alternative combinations of HMOs to those shown in the diagram were actually underweight and that those at the upper end of the weight range were still of ‘normal’ weight. We also don’t know how the weights and body compositions of the babies in the study would compare to those who have been formula-fed: even if breast milk containing high levels of certain HMOs did increase the risk of obesity, the risk with such HMOs could still be lower than that from infant formula.

That some HMOs were shown to have a negative relationship with body weight and/or composition seemed to make the journalist even more confused, since the story ended by stating “However, scientists also found that breast milk could protect against obesity.” The meta-analyses quoted above have demonstrated this, but once again, such a conclusion cannot be drawn from this particular study.
Reporting of current research in the media is invaluable to help increase uptake of its findings, yet the dangerous misinterpretation of the findings of the study by Alderete et al. mean that I hope the story in The Times (not the research study) was ignored by all who read it.

— Celia Taylor


  1. World Cancer Research Fund. Bowel cancer. 2015. [Online]
  2. Faculty of Public Health. A duty on sugar sweetened beverages. A position statement. 2013. [Online]
  3. Alderete TL, Autran C, Brekke BE, et al. Associations between human milk oligosaccharides and infant body composition in the first 6 mo of life. Am J Clin Nutr. 2015. [ePub].
  4. Arenz S, Rückerl R, Boletzko B, von Kries R. Breast-feeding and childhood obesity – a systematic review. Int J Obesity. 2004; 28: 1247-56.
  5. Owen C, Martin R, Whincup P et al. The effect of breastfeeding on mean body mass index throughout life: a quantitative review of published and unpublished observational evidence. Am J Clin Nutr. 2005; 82: 1298-1307.
  6. Harder T, Bergman R, Kallischnigg G et al. Duration of breastfeeding and risk of overweight: a meta-analysis. Am J Epidemiol. 2005; 162:397-403.
  7. Charney E, Goodman HC, McBride M, et al. Childhood Antecedents of Adult Obesity – Do Chubby Infants Become Obese Adults? N Engl J Med. 1976; 295: 6-9.

So Does Breastfeeding Increase Children’s IQ?

News Blog readers will have seen a short report on the Lancet article from Brazil associating breastfeeding with improved IQ.[1] Alas, probably not correct: at least any effect must be very small, according to a recent article that greatly improves on the Lancet paper.[2] First, the authors cite a thorough systematic review published in BMJ Open [3] and conclude that “Any observed associations are best explained by residual confounding.” Second, they conduct an observational analysis of nearly 12,000 children from the Twins Early Development Study. They find that breastfed girls, but not boys, have a significant, but very small, increase in IQ at age 2. They also find that the slope of the increase in IQ beyond age 2 is unaffected by whether or not the child was breastfed. They conclude that, while science cannot exclude tiny effects, the evidence for an effect of breastfeeding on IQ is very weak. Most studies show that the effect goes away or rapidly attenuates as adjustments are made for known confounders. These results are consistent with various experimental studies of nutritional supplements in early life, where null results contrast with positive results from social and educational interventions.

— Richard Lilford, CLAHRC WM Director


  1. Victoria CG, et al. Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. Lancet Glob Health. 2015; 3(4): e199-205.
  2. von Stumm S & Plomin R. Breastfeeding and IQ Growth from Toddlerhood through Adolescence. PLoS One. 2015. [ePub].
  3. Walfisch A, Sermer C, Cressman A, Koren G. Breast milk and cognitive development – the role of confounders: a systematic review. BMJ Open 2013; 3: e003259.

Unpaid Work in the Home

It has long been argued that the cost of environmental degradation should be included in National Accounts and subtracted from Gross National Product. China’s growth postings would be less spectacular if the consequences of air pollution were taken into account, as would Indonesia’s growth rate estimates if deforestation was included. A recent article argues for also taking into account the value of unpaid work bringing up children and caring for the elderly.[1] Women increasingly participate in the labour market with little or no compensating reduction in domestic duties. This results in stress and reduced quality of life. Rai and colleagues suggest that not only should this work be valued and included in the National Accounts, but women should be compensated for the stress that arises. In high-income countries parents are provided with paid parental leave. The motivation here may be largely driven by a desire to increase fertility rather than to improve parents’ wellbeing. It is possible that the economic benefits of improving the dependency ratio, along with those of reducing stress, more than compensate for the upfront costs of the transfers that make this possible. The negative economic consequences of a high-dependency ratio have been discussed in previous blogs.[2] [3] In low-income countries return on investment from supporting parents of young children may be yet greater. The global partner to CLAHRC WM is working with the Africa Population Health Research Center (APHRC) to evaluate the benefit of schemes that promote breastfeeding at work. Here, the benefits include improved outcomes for both mother and child. It is strange how health economics tends to ignore societal effects of interventions on productivity and national wealth.

— Richard Lilford, CLAHRC WM Director


  1. Rai SM, Hoskyns C, Thomas D. Depletion: the cost of social reproduction. Int Fem J Polit. 2014; 16(1): 86-105.
  2. Lilford R. Is Low Fertility a Problem for High-Income Countries, but a Boon For Low-Income Countries? CLAHRC WM News Blog. December 12 2014.
  3. Lilford R. Improving Hospital Care: Not Easy When Budgets are Pressed. CLAHRC WM News Blog. January 23 2015.

The Payback from Improving Availability of Donor Human Milk for Premature Babies

CLAHRC WM is collaborating with the African Population Health Research Centre (APHRC) in the evaluation of donor milk banks in slums (informal settlements) in Kenya. The initiative is led by PATH,[1] which has had considerable success in establishing an altruistic donor service in South Africa. The donor milk is donated to hospital wards caring for premature infants.

There is excellent evidence that donor human milk is superior to ‘formula’ in babies whose mothers are unable to express breast milk. As a result of passive immunity, and also because it has nutritional properties that formula is not able to replicate, donor human milk reduces the risk of neonatal infection.[2] In particular, it reduces the dangerous condition of necrotising enterocolitis (NEC).[3][4] NEC can be fatal and may also require surgery that may have permanent consequences – particularly the ‘short bowel syndrome’. The decreased infection risk resulting from use of donor milk is associated with a measurable decrease in mean length of stay.[5]

One concern is that the mothers of infants who receive donor milk may be less likely to initiate breast feeding at a later date for psychological or physiological reasons. The evidence does not bear out this concern and, if anything, these mothers, perhaps inspired by the altruism of the donors, are more likely to breastfeed.[6][7] If so, this may be expected to augment the benefits of donor milk and also reduce the mother’s risk of developing breast cancer later in life.[8]

The benefits do not seem to end there. There is observational evidence, recently reinforced by a substantial study from Brazil,[9] that cognitive ability in later life is improved by human milk. There is a dose-response effect and the results remain after extensive statistical adjustment for confounders. There is also some experimental (RCT) evidence for a beneficial effect on IQ.[10] Improved IQ is correlated with earning power [11] and, we must assume, payback to society.[12]

To summarise the benefits of breastfeeding we offer the following Influence Diagram (Causal Pathway: Model):

CI - Improving Availability of Donor Human Milk Fig 1

A health economic analysis of promotion of breastfeeding for older children (not premature infants specifically) found that the intervention ‘dominated’ – reduced short-term benefits (less infection) and the contingent cost savings (reduced hospital stays) meant that interventions to promote breastfeeding are cost-saving, not just beneficial for health.[12][13]

There have been two studies of the cost-effectiveness of a donor milk service for premature babies. Both found that the service was cost-effective. The first study was based on a hypothetical baby who was very premature (28 weeks gestational age), rather than an observed mean intervention effect observed at the group level.[14] The calculated benefits might therefore be exaggerated. The second study was based on only 175 propensity scored low birth weight infants.[5] The risk of sepsis decreased with increasing dose of human milk, and total costs obtained from the hospital billing system were lower in proportion to the amount of human milk consumed. However, most infants received some human milk, so the infants could not be divided into a control and intervention population, and the above correlation between outcome and volume of donor milk consumed may have been confounded by factors that determine both access to human milk and sepsis, notwithstanding propensity scoring. Both the above studies were American.

Working with colleagues above, we propose a comprehensive health economic model that takes account of long-term outcomes and that can be populated with country-specific data. The base-case model will be populated with evidence from systematic reviews,[12][13] and we propose to use Bayesian techniques to ‘down weight’ observational evidence using the Turner and Spiegelhalter method.[15]

— Richard Lilford, CLAHRC WM Director
— Celia Taylor, Senior Lecturer


  1. PATH. Models of milk banking in South Africa. Seattle, WA: PATH, 2011.
  2. Arslanoglu S, Ziegler EE, Moro GE. Donor human milk in preterm infant feeding: evidence and recommendations. J Perinat Med. 2010; 38: 347-51.
  3. Lucas A, Cole TJ. Breast milk and neonatal necrotising enterocolitis. Lancet. 1990; 336: 1519-23.
  4. Quigley M, McGuire W. Formula versus donor milk for feeding preterm or low birth weight infants. Cochrane Database Sys Revs. 2014; 4: CD002971.
  5. Patel AL, Johnson TJ, Engstrom JL, Fogg LF, Jegier BJ, Bigger HR, Meier PP. Impact of early human milk on sepsis and health-care costs in very low birth weight infants. J Perinatol. 2013; 33: 514-9.
  6. Arslanoglu S, Moro GE, Bellù R, Turoli D, De Nisi G, Tonetto P, Bertino E. Presence of human milk bank is associated with elevated rate of exclusive breastfeeding in VLBW infants. J Perinat Med. 2013; 41(2): 129-31.
  7. Vázquez-Román S, Bustos-Lozano G, López-Maestro M, et al. Clinical impact of opening a human milk bank in a neonatal unit. An Pediatr (Barc). 2014; 81(3): 155-60.
  8. Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50 302 women with breast cancer and 96 973 women without the disease. Lancet. 2002; 360: 187-95.
  9. Victora CG, Horta BL, Loret de Mola C, Quevedo L, Pinheiro RT, Gigante DP, Gonçalves H, Barros FC. Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. Lancet Glob Health. 2015; 3(4): e199-205.
  10. Horta BL, Victora CG. Long-term effects of breastfeeding: a systematic review. Geneva: World Health Organization. 2013
  11. US Environmental Protection Agency. The benefits and costs of the clean air act, 1970 to 1990, appendix G, lead benefits analysis. Washington, DC: Environmental Protection Agency, 1997.
  12. Renfrew MJ, Pokhrel S, Quigley M, et al. Preventing disease and saving resources: the potential contribution of increasing breastfeeding rates in the UK. UNICEF. 2012.
  13. Kramer MS & Kakuma R. Optimal duration of exclusive breastfeeding. Cochrane Database Sys Revs. 2012; 8: CD003517.
  14. Arnold LDW. The Cost-effectiveness of Using Banked Donor Milk in the Neonatal Intensive Care Unit: Prevention of Necrotizing Enterocolitis. J Hum Lact. 2002; 18(2): 172-7.
  15. Turner RM, Spiegelhalter DJ, Smith GCS, Thompson SG. Bias modeling in evidence synthesis. J R Stat Soc Ser A. 2009; 172: 21–47.