Objective This study aims to determine the rate of gestational diabetes mellitus (GDM) in pregnancies complicated by chronic hypertension and to compare the adverse outcomes in chronic hypertensive pregnancies with and without GDM. Study Design A secondary analysis from a multicenter trial of low-dose aspirin for preeclampsia prevention in women with chronic hypertension. The rate of GDM was evaluated among singleton pregnancies complicated with chronic hypertension and grouped according to their GDM status. Pregnancy outcomes and rates of preterm delivery < 35 weeks and < 32 weeks, preeclampsia, indicated preterm birth, small for gestational age, abruptio placentae, and perinatal death were compared between those with and without GDM. A subgroup analysis comparing women who developed superimposed preeclampsia with and without GDM was studied. Multivariate logistic-regression analysis was used to adjust for potentially confounding factors. Results A total of 763 women met the inclusion criteria: 129 (17%) developed GDM. Parity, race, maternal baseline blood pressure, antihypertensive drug use, and assignment to low-dose aspirin were not significantly different between the groups with and without GDM. Using univariate analysis, maternal age (33 vs. 24%, p = 0.03) and body mass index (88 vs. 57%, p < 0.001) were higher in those who had GDM, whereas the rate of preterm delivery < 32 weeks (12 vs. 5%, p = 0.02) was higher among those without GDM. Using logistic-regression analysis, the rate of composite adverse outcomes (adjusted odds ratio [aOR], 0.77; 95% confidence interval [CI], 0.41-1.47) that included indicated preterm birth, small for gestational age, abruptio placentae, and perinatal death showed no significant differences.Superimposed preeclampsia developed in 34 (26%) women with GDM and in 182 (29%) without GDM. When superimposed preeclampsia was present, it developed at an earlier gestational age among the group without GDM (35 ± 5 vs. 37 ± 3 weeks, p = 0.003), and had higher rates of small for gestational age infants (18 vs. 3%, p = 0.03). After adjustment for confounders, only length of stay in neonatal intensive care unit was longer for those without GDM who developed superimposed preeclampsia (aOR, 0.42; 95% CI, 0.2-0.93). Conclusion Women with chronic hypertension are at a high risk for developing GDM. Outcomes in patients with chronic hypertension and GDM are not significantly different from those with chronic hypertension only.
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