Maternal obesity is associated with shorter duration of breastfeeding CALS Impact Statement

We have studied whether maternal obesity may be contributing to our failure to meet public health goals for breastfeeding. We have found that heavier women breastfeed their infants for a shorter period than normal-weight women. Although social support for breastfeeding explains part of this relationship, biological characteristics of the mother appear to be quite important.

Obesity has increased dramatically in recent years, including among women of childbearing age. In the meantime, we have continued to fail to meet public health targets for continuation of breastfeeding. Data from experimental animals suggested that maternal obesity might be associated with poor lactation performance. We have investigated this possibility among American and Danish women and have sought to understand both biological and non-biological reasons for such an association so as to be able to develop novel interventions to address it.

We investigated this association among white women living in a rural area of upstate New York. We found that, among women who ever breastfed, the heavier they were before conception, the more likely they were to stop breastfeeding early. This was also true of Hispanic–but not black–women living in an urban area of upstate New York. To understand whether the American environment, which is not particularly supportive of breastfeeding, contributed to this association, we also studied it in a nationwide sample of women from Denmark, a country where nearly all newly delivered women breastfeed. We were able to show that in Denmark too the heavier the woman the less long she breastfed her baby.
To investigate why heavier women might have difficulty being as successful at breastfeeding as normal-weight women, we studied both biological factors, such as the hormonal response to the infant’s suckling, and also psychosocial factors, such as a woman’s feeling that she will be able to breastfeed as long as she has planned, that might be involved. In studies carried out among white women living in a rural area of upstate New York, we found heavier women indeed had a lower hormonal response to their infants’ suckling and that their milk “came in” later. However, we were unable to show that psychosocial characteristics were important.

At present, we are testing novel interventions developed from these findings to support improved breastfeeding among obese women.

Overview