While the normal pregnancy is characterized by maternal hemodynamic changes and an insulin resistant state, obesity in pregnancy appears to complicate these expected physiological adaptations to pregnancy. Accordingly, the risk for hypertensive disorders and gestational diabetes (GDM) is reportedly higher in obese and morbidly obese women compared to women who are not obese. In a prospective, multicenter study of more than 16,000 women, Weiss et al.  observed a 2.5-fold greater risk of gestational hypertension, and a 2.6-fold greater risk of GDM among obese versus nonobese women. Risk for these conditions was even greater in a morbidly obese subset, e.g., 3.2- and 4-fold respectively. Similarly, these researchers found the risk for developing preeclampsia was 1.6 and 3.3 times more likely to develop in obese and morbidly obese women, respectively. Results from this study have been confirmed by others [32, 33] and found to be independent of other related factors including age, parity, ethnicity, and family history of chronic diseases.
Frequently, GDM and preeclampsia go hand in hand. Several studies suggest that obesity may be at the "metabolic core" of these conditions. For example, regardless of treatment type or degree of glucose control, Yogev et al.  reported that the risk for developing preeclampsia in women with GDM was significantly greater in obese (10.8%) versus normal weight women (8.2%). Notably, in this study the risk of preeclampsia escalated in obese women with poor glucose control (14.9%), suggesting that tighter glucose control in women with GDM may decrease risk. Barden et al.  found that late-onset preeclampsia in women with GDM was more likely to develop in women who were not only obese but had preexisting hypertension, more severe insulin resistance, subclinical inflammation, and a family history of diabetes and hypertension. Similar to the "metabolic syndrome" in the nonpregnant state, this clustering of risk factors suggests that obese women with GDM and preeclampsia may be at greater risk for cardiovascular disease and type 2 diabetes in later life.
In clinical practice, consideration should be given to screening obese women for GDM and hypertension as soon as possible, preferably upon presentation or during the first trimester. Screening for these conditions should be repeated later in pregnancy if the initial results are negative. Importantly, postpartum follow-up should include advice on achieving a healthful weight and modifying cardiovascular risk factors if they are present.
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