OBJECTIVEThe objective of the study was to prospectively assess the association between lactation duration and incidence of the metabolic syndrome among women of reproductive age.RESEARCH DESIGN AND METHODSParticipants were 1,399 women (39% black, aged 18–30 years) in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, an ongoing multicenter, population-based, prospective observational cohort study conducted in the U.S. Women were nulliparous and free of the metabolic syndrome at baseline (1985–1986) and before subsequent pregnancies, and reexamined 7, 10, 15, and/or 20 years after baseline. Incident metabolic syndrome case participants were identified according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Complementary log-log models estimated relative hazards of incident metabolic syndrome among time-dependent lactation duration categories by gestational diabetes mellitus (GDM) adjusted for age, race, study center, baseline covariates (BMI, metabolic syndrome components, education, smoking, physical activity), and time-dependent parity.RESULTSAmong 704 parous women (620 non-GDM, 84 GDM), there were 120 incident metabolic syndrome case participants in 9,993 person-years (overall incidence rate 12.0 per 1,000 person-years; 10.8 for non-GDM, 22.1 for GDM). Increased lactation duration was associated with lower crude metabolic syndrome incidence rates from 0–1 month through >9 months (P < 0.001). Fully adjusted relative hazards showed that risk reductions associated with longer lactation were stronger among GDM (relative hazard range 0.14–0.56; P = 0.03) than non-GDM groups (relative hazard range 0.44–0.61; P = 0.03).CONCLUSIONSLonger duration of lactation was associated with lower incidence of the metabolic syndrome years after weaning among women with a history of GDM and without GDM, controlling for preconception measurements, BMI, and sociodemographic and lifestyle traits. Lactation may have persistent favorable effects on women's cardiometabolic health.

OBJECTIVETo examine the association between breastfeeding intensity in relation to maternal blood glucose and insulin and glucose intolerance based on the postpartum 2-h 75-g oral glucose tolerance test (OGTT) results at 6–9 weeks after a pregnancy with gestational diabetes mellitus (GDM).RESEARCH DESIGN AND METHODSWe selected 522 participants enrolled into the Study of Women, Infant Feeding, and Type 2 Diabetes (SWIFT), a prospective observational cohort study of Kaiser Permanente Northern California members diagnosed with GDM using the 3-h 100-g OGTT by the Carpenter and Coustan criteria. Women were classified as normal, prediabetes, or diabetes according to American Diabetes Association criteria based on the postpartum 2-h 75-g OGTT results.RESULTSCompared with exclusive or mostly formula feeding (>17 oz formula per 24 h), exclusive breastfeeding and mostly breastfeeding (≤6 oz formula per 24 h) groups, respectively, had lower adjusted mean (95% CI) group differences in fasting plasma glucose (mg/dL) of −4.3 (−7.4 to −1.3) and −5.0 (−8.5 to −1.4), in fasting insulin (μU/mL) of −6.3 (−10.1 to −2.4) and −7.5 (−11.9 to −3.0), and in 2-h insulin of −21.4 (−41.0 to −1.7) and −36.5 (−59.3 to −13.7) (all P < 0.05). Exclusive or mostly breastfeeding groups had lower prevalence of diabetes or prediabetes (P = 0.02).CONCLUSIONSHigher intensity of lactation was associated with improved fasting glucose and lower insulin levels at 6–9 weeks’ postpartum. Lactation may have favorable effects on glucose metabolism and insulin sensitivity that may reduce diabetes risk after GDM pregnancy.

BackgroundHistory of gestational diabetes mellitus (GDM) increases lifetime risk of type 2 diabetes (DM) and the metabolic syndrome (MetS), which increase risk of cardiovascular disease. It is unclear, however, whether GDM increases risk of early atherosclerosis independent of pre‐pregnancy obesity and subsequent metabolic disease.Methods and ResultsOf 2787 women (18 to 30 years) enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study, we studied 898 (47% black) who were free of DM and heart disease at baseline (1985‐1986), delivered ≥1 post‐baseline births, reported GDM history, and had common carotid intima media thickness (ccIMT, mm) measured in 2005‐2006. We used multivariable linear regression to assess associations between GDM and ccIMT adjusted for race, age, parity, and pre‐pregnancy cardiometabolic risk factors. We assessed mediators (weight gain, insulin resistance, blood pressure), and effect modification by incident DM or MetS during the 20‐year period. Of the 898 women, 119 (13%) reported GDM (7.6 per 100 deliveries). Average age was 31 at last birth and 44 at ccIMT measurement for GDM and non‐GDM groups. Unadjusted mean ccIMT was 0.023 mm higher for GDM than non‐GDM groups (P=0.029), but pre‐pregnancy BMI attenuated the difference to 0.016 mm (P=0.109). In 777 women without subsequent DM or the MetS, mean ccIMT was 0.023 mm higher for GDM versus non‐GDM groups controlling for race, age, parity, and pre‐pregnancy BMI (0.784 versus 0.761, P=0.039). Addition of pre‐pregnancy insulin resistance index had minimal impact on adjusted mean net ccIMT difference (0.22 mm). Mean ccIMT did not differ by GDM status among 121 women who developed DM or the MetS (P=0.58).ConclusionsHistory of GDM may be a marker for early atherosclerosis independent of pre‐pregnancy obesity among women who have not developed type 2 diabetes or the metabolic syndrome.

OBJECTIVE-We sought to determine whether childbearing increases incidence of type 2 diabetes after accounting for preconception glycemia and gestational glucose intolerance. RESEARCH DESIGN AND METHODS-A prospective, biracial cohort was examined up to five times during in the multicenter, U.S. population-based Coronary Artery Risk Development in Young Adults Study. The analysis included 2,408 women (1,226 black and 1,182 white) aged 18 -30 years who were free of diabetes and had a fasting plasma glucose (FPG) Ͻ126 mg/dl at baseline. Incident diabetes was diagnosed by self-report, diabetes medication use, FPG Ն126 mg/dl, and/or plasma glucose Ն200 mg/dl after a 2-h oral glucose load. Time-dependent interim birth groups were those with zero and those with one or more births with or without gestational diabetes mellitus (GDM), stratified by baseline parity. Complementary log-log models estimated relative hazards of incident diabetes by interim births adjusted for age, race, family history of diabetes, and baseline covariates (FPG, BMI, education, smoking, and physical activity). RESULTS-Of 193 incident diabetes cases in 42,782 personyears (4.5 cases/1,000 person-years), 84 (44%) had one or more interim births. Among nulliparas at baseline, incident rates per 1,000 person-years were 3.2 (95% CI 2.4 -4.1) for those with no births, 2.9 (1.8 -3.9) for one or more births without GDM, and 18.4 (10.9 -25.9) for one or more births with GDM; adjusted relative hazards (95% CI) were 0.9 (0.6 -1.4) for one or more births without GDM and 3.8 (2.2-6.6) for one or more births with GDM versus no births.CONCLUSIONS-Childbearing did not elevate diabetes incidence among those with normal glucose tolerance during pregnancy (without GDM). GDM conferred the highest risk of developing diabetes independent of family history of diabetes and preconception glycemia and obesity. Diabetes 56: [2990][2991][2992][2993][2994][2995][2996] 2007 E vidence that childbearing is associated with future development of type 2 diabetes in women remains conflicting (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Both nulliparity and multiparity have been associated with higher fasting glucose and insulin levels independent of body size among nondiabetic women (6 -8,13,14). In early crosssectional and retrospective studies, grand multiparity (five or more births) was associated with higher rates of diabetes in women aged Ͼ45 years, unadjusted for age, body size, or socioeconomic status (1,2). In later population-based cross-sectional studies controlling for age, obesity, and socioeconomic status, the association between lifetime parity and prevalent diabetes was direct in three (9 -11) and null in three (3,4,6). Two studies of indigenous groups with high rates of type 2 diabetes reported inverse associations (8,12). In a prospective study of 113,000 white women aged 30 -55 years, the direct association between lifetime parity and incidence of self-reported diabetes was abolished after adjustment for age and obesity, with minimal confounding by family history of...

Objective: To examine whether childbearing is associated with increased visceral adiposity and whether the increase is proportionally larger than other depots. Methods and Procedures: This prospective study examined changes in adiposity assessed via computed tomography (CT) and dual-energy X-ray absorptiometry among 122 premenopausal women (50 black, 72 white) examined in 1995-1996 and again in 2000-2001. During the 5-year interval, 14 women had one interim birth and 108 had no interim births. Multiple linear regression models estimated mean (95% confidence interval (CI)) 5-year changes in anthropometric and adiposity measures by interim births adjusted for age, race, and changes in total and subcutaneous adiposity. Results: We found no significant differences between one interim birth and no interim births for 5-year changes in weight, BMI, total body fat, subcutaneous adipose tissue, or total abdominal adipose tissue. Visceral adipose tissue increased by 40 and 14% above initial levels for 1 birth and 0 birth groups, respectively. Having 1 birth vs. 0 births was associated with a greater increase in visceral adipose tissue of 18.0 cm 2 (4.8, 31.2), P < 0.01; gain of 27.1 cm 2 (14.5, 39.7) vs. 9.2 cm 2 (4.8, 13.6), and a borderline greater increase in waist girth of 2.3 cm (0, 4.5), P = 0.05; gain of 6.3 cm (4.1, 8.5) vs. 4.0 cm (3.2, 4.8), controlling for gain in total body fat and covariates. Discussion: Pregnancy may be associated with preferential accumulation of adipose tissue in the visceral compartment for similar gains in total body fat. Further investigation is needed to confirm these findings and determine whether excess visceral fat deposition with pregnancy adversely affects metabolic risk profiles among women.