Breastfeeding after gestational diabetes pregnancy: subsequent obesity and type 2 diabetes in women and their offspring.

B reastfeeding provides important health benefits to both women and their offspring. Health benefits of lactation for women include a lower risk of breast and ovarian cancer (1) and possibly protection against type 2 diabetes (2). For the offspring, breastfeeding confers protection against both undernutrition and overnutrition during early childhood (3) and may lower risk of developing obesity, hypertension, cardiovascular disease, and diabetes later in life (4–7). Postnatal feeding is one of several critical or sensitive developmental periods (fetal life, adiposity rebound in childhood, and adolescence) hypothesized to result in “metabolic programming” of future chronic disease risk (8,9). In developed countries, there is a robust association between breastfeeding and a lower risk of becoming overweight during childhood and adolescence, even after accounting for maternal obesity and family lifestyle behaviors (10–13). Moreover, greater protection against childhood overweight is associated with more prolonged exclusive breastfeeding. In the U.S., the association of breastfeeding and lower risk of childhood overweight has been observed in Caucasians, but not among low-income Hispanics or AfricanAmericans. Fetal life is another important developmental period influencing future health. Maternal gestational diabetes mellitus (GDM) alters the intrauterine milieu for fetal development that may affect risk factors for chronic disease later in life (14). In some (15–18), but not all (19) studies, offspring of GDM mothers may be more likely to become overweight and to develop type 2 diabetes later in life. A combination of genetic, intrauterine, and postnatal factors contribute to development of childhood obesity and type 2 diabetes in the offspring of women with GDM. Whether breastfeeding affects the future health of offspring of women with GDM is uncertain based on limited and conflicting findings from studies of Native Americans or women with diabetes during pregnancy. Furthermore, no studies that examined the relation of breastfeeding to development of obesity and diabetes in the offspring of women with GDM have controlled for the intrauterine metabolic environment. Lactation may also confer health benefits to women with a history of GDM. Lactation improves glucose tolerance in the early postpartum period, but it is unclear whether future risk of type 2 diabetes is reduced. Here, the evidence for the general population is critically examined for an association of breastfeeding with the risk of obesity and its biological plausibility. Next, evidence is examined among offspring of women with GDM that breastfeeding influences their risk of overweight and type 2 diabetes. Lastly, lactation’s effect on maternal postpartum glucose tolerance and prevention of type 2 diabetes among women with and without previous GDM is examined. Given the equivocal findings for GDM women and their offspring, further research is recommended. BREASTFEEDING AND DEVELOPMENT OF OVERWEIGHT IN OFFSPRING IN THE GENERAL POPULATION — Breastfeeding is recommended as the preferred method of infant feeding for the first year of life or longer, and exclusive breastfeeding is recommended for the first 6 months of life (20). The Institute of Medicine defines exclusive breastfeeding as an infant’s consumption of human milk with no supplementation of any type (no water, juice, nonhuman milk, or foods) except for vitamins, minerals, and medications (21). In the U.S., breastfeeding initiation rates have increased steadily since 1990, but exclusive breastfeeding rates have shown little or no increase over the same period (22). Exclusive breastfeeding at 6 months declined from 18 to 12% between 1981 and 1997 (22) and by 2003 had reached 17% (23). From 1988 to 1994, the prevalence of overweight (defined as BMI 95th percentile) in U.S. youth aged 6–17 years was 11% (24). By 1999 –2002, the prevalence had increased to 16% of youth aged 6–19 years (25). Given that weight tracks from early life into adult life (26–28) and that childhood weight gain and obesity have been linked to chronic diseases later in life (29,30), breastfeeding may be an important contributor to prevention of obesity and its sequelae.