Introduction
Gestational diabetes mellitus (GDM) is diagnosed on the basis of hyperglycemia first detected at any time during pregnancy.1 There is a global rise in the incidence of GDM, with current rates documented to be between 5–36% of pregnant women, dependent on the population, screening and diagnostic criteria.2-4 A significant individual burden is associated with GDM for women and their families including adverse perinatal outcomes, psychological impact and long-term cardiometabolic health consequences.5, 6 There is a growing awareness of the rising worldwide economic implications for health service delivery associated with GDM.7 It is important to identify modifying factors that can reduce GDM and improve pregnancy outcomes for women and infants through targeted use of health resources.
The benefits of breastfeeding to infants are well documented8 and have resulted in ongoing programs worldwide to improve breastfeeding rates. However, less attention has been given to the maternal benefits. Increasing evidence suggests that breastfeeding intensity and the total length of time a woman breastfeeds during her life can positively influence her health. This includes a reduction in type 2 diabetes and an improved cardiometabolic risk profile.9-14
Information is lacking on how breastfeeding length and intensity may impact on glycemic control and the development of GDM in a subsequent pregnancy for women who have had hyperglycemia in a prior pregnancy. Women who have GDM in their first pregnancy may have up to a 13-fold increased risk of GDM in their second pregnancy.15-17Every subsequent pregnancy after a GDM-affected pregnancy has a compounding risk of GDM and a progression to type 2 diabetes.17, 18 We are unaware of any research that has investigated whether breastfeeding reduces this between-pregnancy cumulative risk for the development of GDM. The aim of our breastfeeding length intensity in gestational diabetes (BLIiNG) study is to investigate women who have had GDM in their first pregnancy and assess if length and intensity of breastfeeding mediates GDM risk in a subsequent pregnancy.