Meta-AnalysisBreastfeeding and the maternal risk of type 2 diabetes: A systematic review and dose–response meta-analysis of cohort studies
Introduction
The prevalence of type 2 diabetes is increasing rapidly around the world parallel to the increase in obesity, reduction in physical activity and dietary changes. It has been estimated that 366 million people had diabetes (most of which are of type 2) in 2011 and the number has been projected to increase to 552 million by 2030 [1].
Breastfeeding exerts a major metabolic burden on mothers with an increase in the energy requirement of 400–600 kcal/d [2], [3], [4]. Several studies have reported reduced weight gain and abdominal fatness [5], [6], [7], [8], [9], improved insulin sensitivity [6], glucose tolerance [6], [10], and lipid metabolism [11] and reduced levels of C-reactive protein [12] in breastfeeding mothers. In addition, breastfeeding has been found to be associated with reduced circulating levels of inflammatory markers and increased levels of ghrelin and peptide YY [13]. Epidemiological studies have suggested reduced risk of maternal type 2 diabetes with breastfeeding and several, but not all of these found a stronger association with longer duration of breastfeeding [14], [15], [16], [17], [18]. However, the studies have differed somewhat with regard to the strength of the associations reported and it is not known what is the optimal duration of breastfeeding for prevention of maternal type 2 diabetes. To summarize the available data we conducted a systematic review and meta-analysis of cohort studies of breastfeeding and the risk of maternal risk of type 2 diabetes to clarify the size of the association, if there is a dose–response relationship between greater breastfeeding and type 2 diabetes risk, potential confounding from other risk factors, and whether this partly might be explained by reduced postpartum weight retention by comparing risk estimates adjusted and not adjusted for BMI.
Section snippets
Search strategy
We searched the PubMed, Embase and Ovid databases up to September 19th 2013 for published studies of breastfeeding and type 2 diabetes risk. We used the search terms (“breastfeeding” OR “lactation”) AND diabetes in the search. We scrutinized the references of the identified reports for any further studies. Unpublished data, abstracts, or grey literature was not included. We followed standard criteria for meta-analyses of observational studies [19].
Study selection
To be included, the study had to have a
Results
We identified 6 cohort studies (5 publications) [14], [15], [16], [17], [18] that could be included in the meta-analysis of breastfeeding and type 2 diabetes, including 10,842 cases among 273,961 participants (Table 1, Fig. 1). The number of subjects in each study ranged from 304 to 83,585 and the number of cases ranged from 147 to 3160. One of the studies was conducted among women with gestational diabetes mellitus, two of the studies among American nurses and three studies among women from
Discussion
We found that the longest duration of breastfeeding compared to no breastfeeding was associated with a 32% reduction in the relative risk of type 2 diabetes. In linear dose–response analyses there was a 9% reduction in relative risk for each 12 month increase in lifetime duration of breastfeeding and a non-significant 11% reduction in relative risk for each 3 month increase in duration of breastfeeding per child. There was evidence of nonlinearity in both analyses and the reduction in risk was
Duality of interest
The authors declare that there is no duality of interest associated with this manuscript.
Contribution statement
DA designed the project, conducted the literature search and analyses and wrote the first draft of the paper. DA, TN, PR, LJV interpreted the data, revised the subsequent drafts for important intellectual content and approved the final version of the paper to be published.
Acknowledgment
This project has been funded by Liaison Committee between the Central Norway Regional Health Authority (RHA) and the Norwegian University of Science and Technology (NTNU).
References (32)
- et al.
IDF diabetes atlas: global estimates of the prevalence of diabetes for 2011 and 2030
Diabetes Res Clin Pract
(2011) - et al.
Energy requirements of lactating women derived from doubly labeled water and milk energy output
J Nutr
(2001) - et al.
Maternal weight-loss patterns during prolonged lactation
Am J Clin Nutr
(1993) - et al.
Lactation and weight retention
Am J Clin Nutr
(1997) - et al.
Excess pregnancy weight gain and long-term obesity: one decade later
Obstet Gynecol
(2002) - et al.
Meta-analysis in clinical trials
Control Clin Trials
(1986) - et al.
Energy requirements during pregnancy and lactation
Public Health Nutr
(2005) - et al.
Metabolic adaptation to feeding and fasting during lactation in humans
J Clin Endocrinol Metab
(2002) - et al.
Duration of lactation and maternal metabolism at 3 years postpartum
J Womens Health (Larchmt)
(2010) - et al.
Lactation and changes in maternal metabolic risk factors
Obstet Gynecol
(2007)
The effect of lactation on glucose and lipid metabolism in women with recent gestational diabetes
Obstet Gynecol
Duration of lactation and risk factors for maternal cardiovascular disease
Obstet Gynecol
The effect of breastfeeding on cardiorespiratory risk factors in adult life
Pediatrics
Duration of lactation and maternal adipokines at 3 years postpartum
Diabetes
Duration of lactation and incidence of type 2 diabetes
J Am Med Assoc
Lactation and maternal risk of type 2 diabetes: a population-based study
Am J Med
Cited by (145)
Lipids and lipid signaling molecules in human milk and infant formula, a chemical characterization of relevant biochemical components
2024, Journal of Nutritional BiochemistryPrenatal Counseling and Preparation for Breastfeeding
2023, Obstetrics and Gynecology Clinics of North AmericaPolybrominated diphenyl ethers in type 2 diabetes mellitus cases and controls: Repeated measurements prior to and after diagnosis
2023, International Journal of Hygiene and Environmental HealthOsteopathic intervention for infants with breastfeeding difficulty: A retrospective case series
2023, International Journal of Osteopathic Medicine