Hedderson MM and Ferrara A (2008) High blood pressure before and during early pregnancy is associated with an increased risk of gestational diabetes mellitus. Diabetes Care [10.2337/dc08-1193]

Women with prior gestational diabetes mellitus (GDM) are at an increased risk of high blood pressure in the years following delivery. To investigate whether a relationship exists between high blood pressure before and during early pregnancy and an increased risk of GDM, Hedderson and Ferrara conducted a case–control study using data from a Californian medical care program.

The study included pregnant women who did not have diabetes before pregnancy and who were screened for GDM between 24 and 28 weeks' gestation. The 381 women identified as having GDM (cases) were compared with 942 randomly selected control women with negative screening results. Blood pressure findings during early pregnancy were divided into the following three categories: normotensive (<120/80 mmHg), prehypertensive (120–139/80–89 mmHg), or hypertensive (≥140 and/or ≥90 mmHg or use of antihypertensive medications).

After adjustment for age, ethnicity, gestational week of blood pressure measurement, BMI and parity, women had around a 1.5-fold or twofold increased risk of developing GDM if they were prehypertensive or hypertensive, respectively. In a subgroup analysis, high blood pressure measured during the 5 years before pregnancy also predicted a substantially increased risk of GDM. Furthermore, women with a BMI ≥25.0 kg/m2 before pregnancy who were hypertensive in the first trimester had an almost threefold increased risk.

The findings suggest that routine blood pressure assessments could identify women at high risk of GDM, and enable the early initiation of preventative interventions.