Is breastfeeding best for babies? It's a question that inflames passions, with some mums arguing that nothing but breast will do, whilst others say as long as your baby is getting enough nourishment, then formula is fine.
Now two new studies have emerged that will no doubt add to the controversy.
In one report, academics found that breastfed children were no more likely to be healthier nor more intelligent than bottle-fed children.
But in another report, the claim has been made that breastfed babies do have an advantage – but not because of the intrinsic nutritional value of a mother's milk: rather, that women who breastfeed are likely to be more in tune with their baby's needs.
(Don't shoot the messenger, here: I'm only reporting this stuff!).
In the first study, Dr Cynthia Colen, from Ohio State University, compared siblings fed differently during infancy and found that breast milk is no better than bottled milk at improving long-term health.
She said she wanted her findings to help prevent women who cannot breastfeed from feeling stigmatised, although she insisted she didn't want to challenge the 'breast is best' message championed by such bodies as the Department of Health, which say a mother's milk wards off a host of ills.
Dr Colen said: "Many previous studies suffer from selection bias. They either do not or cannot statistically control for factors such as race, age, family income, mother's employment - things we know that can affect both breast-feeding and health outcomes.
"Mums with more resources - with higher levels of education and higher levels of income - and more flexibility in their daily schedules are more likely to breastfeed their children and do so for longer periods of time."
The NHS recommends that mothers breastfeed for about six months.
Dr Colen said: "I'm not saying breastfeeding is not beneficial, especially for boosting nutrition and immunity in newborns.
"But if we really want to improve maternal and child health, let's also focus on things that can really do that in the long term - like subsidised day care, better maternity leave policies and more employment opportunities for low-income mothers that pay a living wage, for example."
She used data from the 1979 National Longitudinal Survey of Youth, a nationally representative sample of young men and women. She analysed a total of 8,237 children made up of 7,319 siblings and 1,773 'discordant' sibling pairs, where one was breastfed with the other given a bottle.
The study measured BMI (body mass index), obesity, asthma, hyperactivity, parental attachment and behaviour as well as scores predicting academic achievement in vocabulary, reading, maths, intelligence and scholastic competence.
Across all of the families, breastfeeding resulted in better outcomes in BMI, hyperactivity, maths, reading recognition, vocabulary word identification, digit recollection, scholastic competence and obesity.
But when restricted to siblings differently fed within the same families, scores reflecting breastfeeding's positive effects on 10 of the indicators were closer to zero and not statistically significant - meaning any differences could have occurred by chance.
The researchers believe this means the siblings who were all breastfed probably performed better because of other factors, such as socioeconomic status.
Dr Colen said: "Instead of comparing across families we are comparing within families completely taking into account all of those characteristics - both measured and unmeasured - that differ by family such as parental education, household income and race/ethnicity.
"If breastfeeding doesn't have the impact we think it will have on long-term childhood outcomes then even though it's very important in the short-term we really need to focus on other things.
"We need to look at school quality, adequate housing and the type of employment parents have when their kids are growing up.
"We need to take a much more careful look at what happens past that first year of life and understand breastfeeding might be very difficult, even untenable, for certain groups of women.
"Rather than placing the blame at their feet let's be more realistic about what breastfeeding does and doesn't do."
In the second study, 'Breastfeeding, Parenting and Early Cognitive Development', sociologists at Brigham Young University in Provo, Utah, said many studies suggested that breastfed children had higher IQs as they grew up, but they pinpointed two parenting skills as the source of this cognitive boost: responding to children's emotional cues and reading to children starting at nine months old.
Lead study author Ben Gibbs said: "Breastfeeding mothers tend to do both of those things. It's really the parenting that makes the difference.
"Breastfeeding matters in others ways, but this actually gives us a better mechanism and can shape our confidence about interventions that promote school readiness."
Mr Gibbs authored the study with fellow BYU professor Renata Forste for the March issue of the Journal of Pediatrics.
According to their analysis, improvements in sensitivity to emotional cues and time reading to children could yield two to three months' worth of brain development by age four (as measured by math and reading readiness assessments).
Mr Gibbs said: "Because these are four-year-olds, a month or two represents a non-trivial chunk of time.
"And if a child is on the edge of needing special education, even a small boost across some eligibility line could shape a child's educational trajectory."
The study was praised by child development expert Sandra Jacobson, from Wayne State University School of Medicine, in Detroit, Michigan.
She noted that children in the study who were breastfed for six months or longer performed the best on reading assessments because they also 'experienced the most optimal parenting practices'.
She said: "Gibbs and Forste found that reading to an infant every day as early as age nine months and sensitivity to the child's cues during social interactions, rather than breastfeeding per se, were significant predictors of reading readiness at age four years."
The BYU researchers found that the most at-risk children are also the least likely to receive the optimal parenting in early childhood.
Single mums in the labour force, for example, don't have the same luxuries when it comes to breastfeeding and quality time with the children. Parents with less education don't necessarily hear about research-based parenting practices, either.
Ms Forste said: "This is the luxury of the advantaged. It makes it harder to think about how we promote environments for disadvantaged homes. These things can be learned and they really matter. And being sensitive to kids and reading to kids doesn't have to be done just by the mother."
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