Gestational diabetes mellitus. Risk factors, obstetric complications and infant outcomes.

OBJECTIVE: To evaluate risk factors, obstetric complications and infant outcomes in women with gestational diabetes mellitus (GDM).

STUDY DESIGN: We performed a population-based, longitudinal study of 824 women diagnosed with GDM in Nova Scotia, Canada, between 1980 and 1993. Adjusted relative risks (RRs) with 95% confidence intervals (CIs) were estimated through logistic regression.

RESULTS: After controlling for confounding variables, the following were associated with an increased incidence of GDM: maternal age, prepregnancy weight, previous spontaneous or induced abortion (RR 1.41, 95% CI 1.18-1.68), previous stillbirth (RR 1.80, 95% CI 1.08-3.01), previous low birth weight infant (RR 1.48, 95% CI 1.03-2.14), previous high-birth-weight (HBW) infant (RR 1.51, 95% CI 1.18-1.93) and chronic hypertension (RR 2.03, 95% CI 1.19-3.44). The relationship between maternal age and prepregnancy weight with GDM was nonlinear; women over age 35 and with a prepregnancy weight < or = 49 kg or > 65 kg demonstrated an increased risk. Urinary tract infection, polyhydramnios, oligohydramnios, chronic hypertension with superimposed preeclampsia, mild preeclampsia and uterine bleeding of unknown origin occurred more frequently in women with GDM than in those in whom the diagnosis was not made. HBW infants were more likely to be born to women with GDM than to women without GDM. Finally, women with GDM were over twice as likely to undergo cesarean birth (RR 2.30, 95% CI 1.99-2.65).

CONCLUSION: The risk of developing GDM is greatest in women over age 35, when prepregnancy weight is < 49 kg or > 65 kg and in those with chronic hypertension. Pregnancies complicated by GDM are at risk and need to be monitored closely for obstetric complications and adverse infant outcomes.