Whether lactation prevents diabetes mellitus in women after a pregnancy with gestational diabetes is unclear. Investigators classified baseline glucose tolerance of postpartum women with recent ges... Background: Lactation improves glucose metabolism, but its role in preventing type 2 diabetes mellitus (DM) after gestational diabetes mellitus (GDM) remains uncertain. Objective: To evaluate lacta...

OBJECTIVE The 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 METHODS Participants 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. RESULTS Among 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). CONCLUSIONS Longer 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 women9s cardiometabolic health.

OBJECTIVE To 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 METHODS We 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. RESULTS Compared 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). CONCLUSIONS Higher 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.

Background: History 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 Results: Of 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). Conclusions: History 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.

Normal pregnancy is an insulin-resistant state characterized by intensified fluctuations in maternal fasting and postprandial glycemia, hypertriglyceridemia, and increased insulin secretion.¹ Lactation rapidly lowers maternal circulating triglycerides and glucose, lessens insulin secretion, and mobilizes adipose tissue stores.^2-4 Some longitudinal evidence shows that more favorable metabolic profiles persist postweaning,⁵ despite minimal or no weight loss,⁶ but biochemical evidence that directly links lactation with long-term diabetes risk is unavailable. Large, prospective epidemiologic studies of middle-aged or older women of northern European or Asian ancestry showed weak to modest relative reductions in diabetes risk of 3% to 15% per year of lactation,^7,8 or 20% for 6 or more months of lactation.⁹ All studies relied on self-report of diabetes without biochemical testing or other assessments across the childbearing years or beyond.^7-9 Furthermore, none considered gestational diabetes (GD), a strong risk factor for type 2 diabetes in young women,^10-12 although a retrospective subanalysis among women reporting GD after incident diabetes found no association.⁷ Thus, risk estimates may be biased away from the null owing to unmeasured confounding or reverse causation from cardiometabolic risk factors, GD status, perinatal outcomes, and differences in lactation duration among older vs younger women, or biased toward the null by exclusion of high-risk younger women who had transitioned to diabetes many years prior to study baseline. The lack of longitudinal biochemical testing, older age of study participants at baseline, and the inability to evaluate antecedent biochemical and perinatal parameters, including GD status, diminish the validity for this entire body of evidence.

OBJECTIVES: To estimate the incidence, describe the mortality, and identify independent predictors of peripartum cardiomyopathy, a very serious cardiovascular complication of pregnancy associated with maternal morbidity and mortality among otherwise healthy women without prior heart disease. METHODS: We identified all cases of diagnosed heart failure that occurred among women within 1 month before to 5 months after delivery of a liveborn neonate in Kaiser Permanente Northern California delivery hospitals between 1995 and 2004. Incident peripartum cardiomyopathy was confirmed from medical records documenting dilated cardiomyopathy with reduced left ventricular systolic function after excluding women with prior heart failure or valvular disease. Data sources included medical records, electronic clinical databases, and state birth and death files. RESULTS: Among 227,224 eligible women, we confirmed 110 recognized peripartum cardiomyopathy cases (incidence: 4.84 per 10,000 live births, 95% confidence interval 3.98–5.83). Independent predictors included maternal age of 25 years or older, non-Hispanic African American and Filipino groups, parity of 4 or greater, multiple gestation, severe anemia, pre-existing and pregnancy-related hypertensive disorders, and hemolysis, elevated liver enzymes, low platelets syndrome. Maternal death rate (per 1,000 person-years) was higher among cases (6.12) than noncases (0.23; P<.001). Neonates whose mothers developed peripartum cardiomyopathy experienced poorer clinical outcomes. CONCLUSION: Within a large, diverse northern California population, 1 of every 2,066 women delivering a liveborn neonate had recognized, confirmed peripartum cardiomyopathy, which was associated with higher maternal and neonatal death rates and worse neonatal outcomes. Several readily available patient characteristics can be used to identify women at risk for this severe pregnancy complication. LEVEL OF EVIDENCE: II