Spontaneous preterm delivery and gestational diabetes: the impact of glycemic control

Opinions differ whether the rate of spontaneous preterm delivery (sPTD) increases in pregnancies complicated with GDM. We sought to characterize, which factors may influence the rate of sPTD in GDM.

We conducted a retrospective study with 1,526 GDM patients, all treated at the same center by the same diabetic protocol using self-blood glucose monitoring. The rate of sPTD was compared to that of 10,560 non-diabetic women. Eligibility for the study was limited to women with a singleton pregnancy with spontaneous onset of delivery before 37 weeks of gestation with no history of chronic maternal illness, i.e., chronic hypertension or development of preeclampsia in the current pregnancy, and no clear indication for preterm delivery. Mean blood glucose < 105 mg dl(-1) was defined as well controlled.

Overall, no difference was found in the rate of sPTD in GDM (163/1,526, 10.7%) in comparison to non-GDM patients (1193/10,560, 11.3%, P = 0.2). In the GDM group, a comparison between women with and without sPTD found no difference in maternal age (28.1 +/- 6 vs. 28.2 +/- 6), prepregnancy BMI (28.1 +/- 5 vs. 27.8 +/- 6), rate of nulliparity (38 vs. 34%) or ethnicity origin. GDM patients with sPTD were characterized by higher glucose values in the OGTT and higher mean blood glucose (114 +/- 16 vs. 106 +/- 14, P < 0.0001). Sixty-five percent of patients with sPTD versus. 46% in the non-sPTD were in poor glycemic control (P = 0.004). Multiple logistic regressions, when the dependent variable was sPTD revealed that mean blood glucose (OR 1.94 95% CI 1.25-3.0), history of sPTD (OR 3.25 95% CI 2.1-4.8) and parity (OR 1.49 95% CI 1.05-2.2) were contributing factors.

The rate of sPTD in GDM is not increased in comparison to non-GDM patients, but reaching established levels of glycemic control may reduce the rate of sPTD in GDM.