NEW YORK (Reuters Health) - The heavier a woman is when she becomes pregnant, the less likely she is to stick with breast-feeding long-term, a new study from Denmark shows.
While U.S. studies have also shown that heavier women are less likely to nurse their infants, the current investigation took place in a country where breast-feeding is nearly universal and receives plenty of social support, suggesting that there is some biological mechanism by which excess weight interferes with breast-feeding success, the study’s authors say.
“It’s some sort of hormonal imbalance, potentially, we don’t know for sure,” Dr. Jennifer L. Baker of Copenhagen University Hospital, the study’s lead author, told Reuters Health, pointing out that one study found that secretion of the hormone prolactin was blunted in overweight nursing women. But the findings also show, she added, that with plenty of assistance even very obese women can breast-feed successfully.
To better understand factors that might be involved in early termination of breast-feeding by heavier women, Baker and her team looked at 37,459 women Danish women who delivered infants between 1999 and 2002, following them for 18 months after they gave birth.
Among women who were morbidly obese (body mass index of 40 or greater), 14.4 percent had stopped exclusive breast-feeding by the time their child was a week old, compared with 3.5 percent of normal-weight women. Throughout the course of the study, the likelihood of stopping breast-feeding rose with BMI.
Given the high prevalence of overweight and obesity among women of reproductive age in the US — the percentage of women in their 20s and 30s have BMIs of 40 or greater is at an historic high of 8 percent — the findings are worrisome, Baker and her team note.
However, even the heaviest women in the current study were able to initiate and continue breast-feeding, which is hopeful, Baker said.
“We clearly could have a problem, but if we could improve the overall situation I think we could help a lot more women become successful at breast-feeding,” said Baker. For example, she pointed out, lactation consultants can be extremely helpful for women who are having difficulties.
“Maternal obesity itself is really just an indicator that a woman may need additional assistance in order to successfully breast-feed her infant,” she concluded.
SOURCE: American Journal of Clinical Nutrition, August 2007.