"This is the purest nonsense", Carlsen says. "Boys are not less loved by their mothers than girls. We can blame biology here, not mothers. All these relationships can be explained by one and the same cause, namely the level of male hormones during pregnancy.""We find it very interesting that almost all of the factors previously shown to be associated with breastfeeding can be explained by changes in testosterone levels in the mother during pregnancy," he adds. Message to new mothers: Relax! The researcher stresses that it is inappropriate to blame mothers who are unable to breastfeed as much as they are advised. Mothers should not worry that their children will be sicker than children who are breastfed. And even though a child's health risks have already been established at birth, the differences are so small that they can only be detected when looking at large groups. Carlsen says mothers should not worry about this. "If you are pregnant, you should live as healthy a lifestyle as possible: quit smoking, cut back on your consumption of coffee and tea, and avoid alcohol", he says. "And when you give birth, you will do the best that you can, if you want to breastfeed."The research adds that if a mother has a hard time breastfeeding, she should just relax and enjoy her newborn. "Don't let overzealous health professionals give you a guilty conscience" he says. No breast milk benefit The researchers reviewed more than fifty international studies about the relationship between breastfeeding and health. Most studies concluded that the more children are nursed, the healthier the children - which on the surface is correct, Carlsen says. "But even if this is statistically true, it is not because of breastfeeding itself. There are very few studies that have examined the underlying controls on breastfeeding ability" he adds. The largest study that has been done on breastfeeding and health was undertaken in Belarus. More than 17 000 women and children were studied, and the children were followed until they were six years old. This study cuts the legs out from underneath most of the assertions that breastfeeding has health benefits, the researchers say. For example, the Belarus study found no signs that asthma and allergies were less prevalent in children who were nursed for longer than children who were nursed less.

The only area where the study concluded that breastfeeding confers a benefit was in mental abilities. "It appears that children who are breastfed have a small IQ advantage", Carlsen says. "But this needs to be confirmed in new, carefully planned and conducted studies." Breastfeeding should be out of politics The researcher believes it is time for nursing enthusiasts to calm down. "There are many good reasons to breastfeed. But concern for the child's health is not one of them. There is no reason why women who are struggling to breastfeed should have to go around feeling guilty, or think that they are giving their child a poor start in life if they can't nurse. Baby formula is as good as breast milk", Carlsen says. Carlsen adds that it is far worse for babies to have a tired, stressed-out mother with a guilty conscience, than to forgo breast milk. The health aspects of breastfeeding should be left out of political arguments, he says. Breastfeeding environmentally soundCarlsen believes that the strongest reason to encourage mothers to breastfeed is because of the environment. Breastfeeding avoids the environmental costs of producing bottles and formula, and the energy consumption that goes with sterilizing bottles. Breastfeeding is also the right approach for developing countries, where economics, hygienic conditions and the lack of natural resources makes breastfeeding superior to bottle feeding. Exercise and diet A study is underway to see if exercise has an impact on testosterone levels, and thus perhaps also on breastfeeding.

"We would also like to have funding to implement a larger study on the effect of diet and nutrition counselling for pregnant women. There is still much we do not know", Carlsen said.

Source: Norwegian University of Science and Technology