Primary prevention
It is reasonable to recommend a high-quality diet, weight gain within the Institute of Medicine guidelines, and physical activity to women during pregnancy.[21][33]
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Evidence on whether this reduces the risk of gestational diabetes mellitus (GDM) remains unclear and further high-quality evidence is needed. A randomized study in Finland demonstrated a significant (39%) decrease in the incidence of GDM in high-risk women who received a lifestyle intervention that combined dietary counseling, physical activity, and limitation of weight gain compared with the control group.[34] A systematic review found that combined diet and exercise interventions during pregnancy may be effective at reducing the risk of GDM, and reducing gestational weight gain compared with standard care, but the authors concluded that further high-quality evidence is needed.[35][36]
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Meanwhile, meta-analysis of interventions aiming specifically to prevent the development of GDM in women with overweight and obesity showed no benefit of interventions (diet, exercise, or combination) in preventing GDM when applied during pregnancy.[37]
In pregnant women with overweight and obesity, there is evidence to suggest that multidisciplinary prenatal care (including continuity of obstetric provider; regular weigh-ins; brief intervention by a food technologist to ask about eating habits and provide advice on healthy eating; and clinical psychology management to assess for psychological factors involved in eating patterns, symptoms of depression/anxiety, and presence of stressful life events) and general prenatal dietary and lifestyle interventions may reduce the amount of maternal weight gain during pregnancy.[38] Two randomized controlled trials have now found that starting metformin in the second trimester does not reduce the risk of GDM in women with overweight or obesity.[39][40]
Secondary prevention
All women should continue taking folic acid (started before conception) for at least the first 12 weeks of gestation to reduce the risk of neural tube defects.[1]
Prevention of type 2 diabetes in women with prior GDM
Since women with GDM are at an increased risk for type 2 diabetes, they should be screened for the condition at 4-12 weeks postpartum, and every 1-3 years depending on whether results are abnormal or not.[1][123] Given the low rates of oral glucose tolerance test uptake, screening with hemoglobin HbA1c or fasting glucose should be considered within the first year postpartum for those who do not complete an oral glucose tolerance test.[123]
Women with impaired fasting glucose or impaired glucose tolerance postpartum should be placed on medical nutrition therapy and start an exercise program and/or offered metformin to reduce their risk of developing diabetes.[1] Data from the Diabetes Prevention Program demonstrated that for individuals with prediabetes and a history of GDM (12 years prior on average), metformin use was equivalent to lifestyle modification; both equally reduced the risk of type 2 diabetes by 50% compared with placebo, and this risk reduction persisted for 15 years.[130]
Women with a history with GDM should be referred to diabetes prevention programs. In the US, many insurances cover the National Diabetes Prevention Program (NDPP) for women with prior GDM, although this group of individuals is underrepresented in NDPP participants, suggesting the need for increased referrals. In a large prospective cohort study of high-risk women with a history of GDM with 28 years of follow-up, having optimal levels of five modifiable risk factors (BMI <25, high-quality diet, moderate alcohol consumption [5-14.9 g/day], regular exercise [≥150 minutes/week of moderate intensity or ≥75 min/week of vigorous intensity] and no current smoking) was associated with a more than 90% relative reduction in the risk of incident type 2 diabetes after adjustment for other major diabetes risk factors. The beneficial associations were consistently seen, even among women with overweight/obesity and among women with greater genetic susceptibility to type 2 diabetes.[141] Another study demonstrated that a modified diabetes prevention program-based lifestyle intervention in the postpartum period was associated with decreased postpartum weight retention in women with GDM.[142] Further study is needed to establish if intervention in the postpartum period is associated with a decreased risk of type 2 diabetes.
Breastfeeding may be beneficial for women who have had GDM and is recommended by the ADA and American Heart Association (AHA) in order to reduce the risk of subsequent type 2 diabetes.[1][123] There are limited data to suggest that lactation is associated with an improvement in fasting and postprandial hyperglycemia in women with recent GDM.[143] Population-based data also suggest that a greater length of lifetime lactation is associated with a lower risk for type 2 diabetes.[144] GDM may be associated with delayed lactogenesis. Therefore early specialist lactation support may be required.[145]
Prevention of cardiovascular disease in women with prior GDM
Women with GDM have a higher risk of cardiovascular events postpartum that is independent of the development of type 2 diabetes.[132] A history of GDM is considered a cardiovascular risk factor by the AHA and provides an opportunity for early cardiovascular risk surveillance modification.[132][146] Therefore, lifestyle changes including diet with the goal of weight loss if BMI in the overweight or obese category, or maintenance of weight if lean; exercise; and smoking cessation are recommended to reduce the risk of cardiovascular disease. The AHA advises that the postpartum and interpregnancy time frames are critical time windows in which implementation of a comprehensive multidisciplinary plan and careful consideration of cardiovascular risk factors are important to reduce adverse maternal outcomes.[123] Referral to lifestyle interventions such as the NDPP or programs incorporating NDPP elements is recommended.[123] The US Department of Health and Human Services recommends 150 minutes of moderate-intensity exercise per week in the postpartum period.[123] There are several ongoing translational studies of the NDPP targeting women in the first postpartum year that have shown promise in decreasing postpartum weight retention.[142][147] In addition to lifestyle interventions, weight loss treatment may include pharmacologic options, such as glucagon-like peptide-1 (GLP-1) receptor agonists, or bariatric surgery for eligible patients.[123]
Identification of barriers and implementation of solutions that incorporate different team members to improve retention of individuals are essential given that up to 40% of women do not participate in postpartum care and only an estimated 18% to 25% of postpartum patients with adverse pregnancy outcomes (including GDM) or chronic health conditions are seen by a primary care clinician within 6 months of delivery.[123] The American College of Obstetricians and Gynecologists and AHA have released a joint presidential advisory calling for enhanced collaboration and coordination of care between obstetrician-gynecologists and cardiologists, particularly for cardiovascular risk factor screening and integrated models of care.[148]
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