LLLI Center for Breastfeeding Information

Journal Abstract and Review of the Month for January 2006

"Duration of Lactation and Incidence of Type 2 Diabetes"

Authors:
Alison M. Stuebe, MD
Janet W. Rich-Edwards, ScD
Walter C. Willett, MD, DrPH
JoAnn E. Manson, MD, DrPH
Karin B. Michels, ScD, PhD

JAMA. 2005 Nov 23; 294(20):2601-10.

Abstract and Review:

The association between lactation history and development of type 2 diabetes was studied in two Nurses' Health Studies. The Nurses Health Study (NHS) began in 1976, and enrolled 121,700 women. The second study, Nurses Health Study II (NHSII) began in 1989 and enrolled 116,671 women. The population of the studies was composed of registered nurses. Every two years participants completed follow-up questionnaires.

Lifetime lactation history was stratified into six groups: none, 0-3 months, 3-6 months, 6-11 months, 11-23 months, and more than 24 months. The effect of exclusive breastfeeding versus total duration of breastfeeding on diabetes risk was compared. It was found that each year of exclusive breastfeeding was associated with greater diabetes risk reduction than total breastfeeding. Longer durations of breastfeeding per pregnancy were associated one year's lactation for one child resulting in a 44% reduction in age-adjusted risk as compared with one year's lactation between two children resulting in a 24% reduction in risk.

In addition, the researchers assessed whether using medication to suppress lactation was associated with subsequent risk of diabetes among women who never breastfed. Use of medication to suppress lactation was associated with an increased risk of type 2 diabetes compared to women who never breastfed but did not use such medication. This may raise the possibility that interfering in the hormonal changes involved in lactation may have significant metabolic consequences. Animal data lend tentative support to this hypothesis.

The results found that among parous women in two large US cohorts of women increasing the duration of lactation was associated with a reduced risk of type 2 diabetes. Human studies suggest that lactation affects insulin and glucose homeostasis. For each additional year of lactation, women with a birth in the prior 15 years had a decrease in the risk of diabetes of 15% among the NHS participants, and of 14% among the NHS II participants. With type 2 diabetes mellitus affecting nine million adult women in the US, and absorbing $1 of every $10 spent on health care, the results of this research indicate that breastfeeding is a way to decrease the incidence of diabetes and decrease health care expenses.

This paper is categorized by the following keywords:

Diabetes

Duration

An additional abstract of this article, and information about how to acquire the entire article, may be viewed at this link.