Objective: To investigate the influence of pre-pregnancy weight on delivery outcome and birth weight in potential diabetic women with normal glucose tolerance.

Design: Retrospective Cohort study

Material and Method: The medical records of 660 pregnant women, who attended the antenatal clinic and delivered at Siriraj Hospital between January 2003 and December 2005, were reviewed and analyzed. They all had the known pre-pregnancy weight and were at risk of gestational diabetes with the normal glucose tolerance. Any pregnant women without pre-pregnancy weight recorded were excluded from the present study. They were classified into two groups according to the pre-pregnancy BMI, one was the overweight group (BMI ≥27 kg/m²) and the other was the normal weight group (BMI 20-25 kg/m²). Information of the complications of pregnancy, the route of delivery, birth weight, and neonatal outcomes were collected and analyzed.

Results: The risks of adverse pregnancy outcomes in overweight women, after adjusting for the confounding factors, were significantly increased, including pre-eclampsia (OR 3.87, 95% CI 2.09-7.25, p<0.001), cesarean delivery (OR 2.22, 95% CI 1.45-3.39, p<0.001), cephalopelvic disproportion (OR 2.15, 95% CI 1.35-3.42, p = 0.001), and macrosomia (OR 7.59, 95% CI 1.98-29.09, p<0.001).

Conclusion: Even though the screening test for gestational diabetes mellitus is normal, the overweight women still have several adverse pregnancy outcomes.

Keywords: Birthweight, Delivery outcome, Normal glucose tolerance, Overweight, Pregnancy