News & Research

Lactation and maternal risk of type 2 diabetes: a population-based study, by Eleanor Bimla Schwarz and colleagues. American Journal of Medicine 123:863.e1–863.e6, 2010

What is the problem and what is known about it so far?

An estimated 10% of all American women who are 20 years of age or older have diabetes. For this reason, it is important to learn about behaviors that could raise or lower a woman’s chances of getting the disease. Some behaviors, such as eating a healthy diet and getting enough exercise, are well known to affect the likelihood of getting diabetes. Less is known about whether a woman’s decision to breastfeed her children may affect her chances of getting diabetes.

Studies of women who have had recent gestational diabetes (diabetes that is first diagnosed during pregnancy and increases the risk of later type 2 diabetes) have found that breastfeeding improves their body’s use of glucose and fats. Other studies have found that breastfeeding for longer periods of time may reduce a woman’s diabetes risk. However, more study is needed to find out whether breastfeeding has to be consistent and to take place for a specific length of time to reduce the risk of diabetes.

Why did the researchers do this particular study?

The researchers wanted to look at whether the length of time a woman breastfeeds, whether breastfeeding is the only way the baby is fed, and whether breastfeeding is done consistently affect a woman’s chances of getting diabetes later.

Who was studied?

The study included 2,233 women between the ages of 40 and 78 who were members of a large health maintenance organization (HMO) in California and were participating in a larger study. Of the participants, 1,828 were mothers, and more than half of those had breastfed their children for at least 1 month.

How was the study done?

The researchers looked at how many women who had breastfed their babies went on to get diabetes. They specifically looked at how long, how consistently, and how exclusively the women had breastfed. They also took many other factors into account, including age, race, education, number of pregnancies, exercise, tobacco and alcohol use, family history of diabetes, body mass index (a measure of overweight), and whether the women had had a hysterectomy.

What did the researchers find?

Women who had consistently breastfed all of their children for more than 1 month were about as likely as women who had never given birth to have gotten diabetes later. Mothers who did not breastfeed exclusively were more likely to have gotten diabetes than mothers who exclusively breastfed for 1–3 months.

What were the limitations of the study?

All participants in this study belonged to a large HMO that has been found to have fewer members at very high or very low income levels than the general public and to have members that tend to be more educated than the general public. This could have affected the study results. The women in this study also may have inaccurately reported their breastfeeding activity. Studies have shown that women who breastfeed for shorter periods of time might report doing so for longer, whereas those who breastfeed for longer time periods might report doing so for shorter lengths of time. In addition, obesity, trouble processing insulin, and pregnancy complications that have been linked to glucose problems and heart disease may cause some women to have trouble successfully breastfeeding. Therefore, some of the women who did not breastfeed or did so for a shorter time already may have had health issues that increased their risk for diabetes.

What are the implications of the study?

This study adds more evidence that women who do not breastfeed their children are more likely to get diabetes later. Although breastfeeding for the first 6 months of life is recommended for infant health, only 14% of American mothers do so. All mothers should be encouraged to breastfeed all of their infants for at least 1 month, if not longer.

FOR MORE INFORMATION

Gestational diabetes

Diabetes care after pregnancy

ADA’s Uncomplicated Guide to Diabetes Complications