Feeling guilty that you didn't breastfeed your children enough - or at all? Relax. New research shows that breast milk is not as important for either the mother or the child's health.
Researchers at the Norwegian University of Science and Technology have found that the association between breastfeeding and healthy children is not as strong as has previously been believed. It is true that breastfed infants are slightly healthier than bottle-fed babies. But apparently it is not the milk that makes the difference. Instead, the baby's overall health is all determined before he or she is born. So why do so many studies associate breastfeeding with better health for young babies. The answer is simple: If a mother is able to breastfeed, and does so, this ability is essentially proof that the baby has already had an optimal life inside the womb.
Hormones are a determinant
Researchers at NTNU's Department of Cancer Research and Molecular Medicine have recently found a correlation between the level of male hormones (androgens) in pregnant women and how much the women breastfed after birth.
"Pregnant women who have higher levels of androgens breastfeed less," says Professor Sven M. Carlsen. "Probably, this is a direct effect of hormones that simply limit nursing ability, by reducing milk production in the breast."
For example, there is a clear link between testosterone and breastfeeding ability. In fact, until 1980, when more suitable drugs were introduced, testosterone was used to stop milk production in circumstances where it was desirable.
"This was one of the reasons that we wanted to investigate whether the effects attributed to mother's milk really should be attributed to hormonal factors in pregnant women", says Carlsen.
Not a matter of will
Carlsen and colleagues have for years researched the connections between the conditions for the foetus in utero, and the effects these conditions have on the newborn. Among other things, they have looked at the relationship between testosterone levels and various risk factors that are believed to affect breastfeeding.
Women who are smokers, or are overweight, or who have the hormonal disorder polycystic ovary syndrome (PCOS) tend to breastfeed less than their peers. All the women in these groups have higher levels of testosterone in their bodies when they are pregnant.
In contrast, the older a woman is, the more likely she is to breastfeed. All these relationships can be explained by the level of testosterone, Carlsen says. "It's thus not the woman's will to breastfeed. Women who had more testosterone in their bodies during pregnancy feel the effects of a hormone that limits breastfeeding. That is clearly why it is not as easy to breastfeed."
Placenta is key
Carlsen believes that it is the placenta, not breast milk, that has more of an effect on children's health.
"What happens is that there are hormones that come from the foetus that are converted to testosterone and oestrogen in the placenta -- if the process goes as it should. This is an energy intensive process. If the placenta does not have enough energy, a portion of the testosterone that would have been converted to oestrogen is in fact not converted. Then what happens is that the testosterone goes to both the mother and child, and probably affects both of them", he said.
For the mother, this means reduced development of glandular tissue in the breasts, so that the ability to make milk does not develop optimally during pregnancy. This translates into less or no milk breast milk.
For the child, it looks as if increased exposure to testosterone as a foetus can lead to an increased incidence of obesity, type 2 diabetes and polycystic ovary syndrome in girls.
Much fuss
Breastfeeding is less common in younger women, smokers, women who have had preeclampsia or are overweight, or with lower birth weight or premature babies, or in women with PCOS, and when the child is a boy.
There are a number of models that are used to explain this - erroneously, Carlsen and his colleagues say. For example, it is claimed that the bond between a mother and her child will not be as strong if the baby is a boy than if the baby is a girl.