Physical activity of relatively high intensity in mid-pregnancy predicts lower glucose tolerance levels

Physical activity (PA) is recommended as part of therapy for patients with impaired glucose tolerance. Whether such recommendations are also justified for pregnant women is less well established. We investigated the association between PA and glucose tolerance in pregnancy.

A non-selective sample of 217 pregnant women was recruited at a routine 20 week ultrasound examination. Participants answered the International Physical Activity Questionnaire (IPAQ) about frequency, intensity and duration of daily physical activity in the past 7 days and underwent oral glucose tolerance testing (OGTT) between 24 and 28 weeks. A subset of 72 overweight/obese pregnant women wore a pedometer for 1 week with assessment of IPAQ score and pedometric correlations to this.

Of the sample, 177 attended for OGTT; 51% were overweight or obese. The mean (SD) fasting glucose was 4.5 (0.4) mmol/L, and 12% had gestational diabetes mellitus. Only one-third engaged in vigorous PA. After adjustment for pre-pregnancy BMI, age and parity, those engaging in vigorous PA had significantly lower fasting glucose levels (by 0.15 mmol/L, 95% CI 0.03-0.27) compared with those not vigorously active. This decrease was similar in both normal and overweight/obese women. There were fewer cases of gestational diabetes (p = 0.03) among the vigorously active women (3/56; 5%) than among those who were not active (19/121; 16%). No association with glucose tolerance was observed for physical activity of moderate intensity.

Only vigorous physical activity appears beneficial with respect to maternal glucose tolerance, both among normal, overweight and obese women.