Exercise training in pregnancy reduces offspring size without changes in maternal insulin sensitivity. Exercise during pregnancy improves maternal glucose screen at 24-28 weeks: a randomised controlled trial. Supervised home-based exercise may attenuate the decline of glucose tolerance in obese pregnant women. Regular exercise during pregnancy to prevent gestational diabetes: a randomized controlled trial. Prevention of gestational diabetes: feasibility issues for an exercise intervention in obese pregnant women.
Epidemiological studies have identified the importance of the in utero environment in providing a healthy start to life. Previous studies have suggested that the maternal environment, in particular a reduction in maternal insulin sensitivity, contributes significantly to fetal growth. Regular aerobic exercise, through an effect on maternal insulin sensitivity, may influence offspring size by regulating nutrient supply to the fetus.
                The aim of the study was to determine the effects of aerobic exercise training in the second half of pregnancy on maternal insulin sensitivity and neonatal outcomes.
                We conducted a community-based, randomized, controlled trial of exercise in pregnancy.
                Eighty-four healthy nulliparous women (mean +/- sd, age, 30 +/- 4 yr; body mass index, 25.5 +/- 4 kg/m(2)) participated in the study.
                Subjects participated in a home-based stationary cycling program from 20 wk gestation to delivery.
                Maternal insulin sensitivity, neonatal auxology, body composition, and growth-related peptides in cord blood were measured.
                Offspring of exercisers had lower birth weight (sd score, control, 0.23 +/- 0.8; exercise, -0.19 +/- 0.9; P = 0.03) and body mass index at birth (sd score, control, 0.40 +/- 0.9; exercise, -0.01 +/- 0.09; P = 0.04). The reduction in maternal insulin sensitivity in late gestation was not affected by exercise (P = 0.45) and was unrelated to offspring size. Exercise offspring had lower cord serum IGF-I (P = 0.03) and IGF-II (P = 0.04).
                Regular exercise was associated with lower birth weights and reduced cord concentrations of growth-related peptides, suggesting an influence of exercise on endocrine regulation of fetal growth. These effects on offspring growth were not associated with an exercise training effect on maternal insulin sensitivity. The influence of an exercise programme performed by healthy pregnant women on maternal glucose tolerance was studied.
                A physical activity (PA, land/aquatic activities) programme during the entire pregnancy (three sessions per week) was conducted by a qualified instructor. 83 healthy pregnant women were randomly assigned to either an exercise group (EG, n=40) or a control (CG, n=43) group. 50 g maternal glucose screen (MGS), maternal weight gain and several pregnancy outcomes were recorded.
                Significant differences were found between study groups on the 50 g MGS. Values corresponding to the EG (103.8 ± 20.4 mg/dl) were better than those of the CG (126.9 ± 29.5 mg/dl), p=0.000. In addition, no differences in maternal weight gain and no cases of gestational diabetes in EG versus 3 in CG (7%) (p>0.05) were found.
                A moderate PA programme performed during pregnancy improves levels of maternal glucose tolerance. The significant deterioration of insulin sensitivity and glucose tolerance during pregnancy can have serious health implications for both the pregnant woman and her baby. Although it is well established that regular exercise benefits insulin sensitivity in the nonpregnant population, the effect on glucose tolerance in obese pregnant women is not known. The purpose of this study was to investigate the effect of a supervised 10-week, home-based, exercise programme, beginning at week 18 of gestation, on glucose tolerance and aerobic fitness in previously sedentary obese women.
                Twelve sedentary obese women were randomized into an exercise (EX; n=6) or control (CON; n=6) group at 18 weeks of gestation. Those randomized to EX engaged in 10 weeks of supervised home-based exercise (three sessions a week of stationary cycling), while those in the CON group maintained their usual daily activity. Their glucose and insulin responses to an oral glucose tolerance test (OGTT), as well as their aerobic fitness, were assessed both pre- and postintervention.
                Reduced glucose tolerance in the CON, but not EX, group was indicated by a tendency postintervention towards higher blood glucose levels at 1h of the OGTT (P=0.072). Furthermore, at 2h of the postintervention OGTT, blood glucose tended to remain elevated from baseline in the CON (P=0.077). There was also a trend towards increased fitness in the EX (P=0.064), but not the CON group.
                Regular aerobic exercise begun during pregnancy may have favourable effects on glucose tolerance and fitness in obese women, and warrants further investigation in a larger sample population. To assess whether exercise during pregnancy can prevent gestational diabetes and improve insulin resistance.
                A total of 855 women in gestational week 18-22 were randomly assigned to receiving a 12-week standard exercise program (intervention group) or standard antenatal care (control group). The exercise program followed standard recommendations and included moderate-intensity to high-intensity activity 3 or more days per week. Primary outcomes were gestational diabetes and insulin resistance estimated by the homeostasis model assessment method. For the power calculation, we assumed a gestational diabetes prevalence of 9% in the control group and a prevalence of 4% in the exercise group (risk difference of 5%). Under these assumptions, a two-sample comparison with a 5% level of significance and power of 0.80 gave a study population of 381 patients in each group.
                At 32-36 weeks of gestation there were no differences between groups in prevalence of gestational diabetes: 25 of 375 (7%) in the intervention group compared with 18 of 327 (6%) in the control group (P=.52). There were no differences in insulin resistance between groups when adjusting for baseline values. Only 55% of women in the intervention group managed to follow the recommended exercise protocol. No serious adverse events related to physical exercise were seen, and the outcomes of pregnancy were similar in the two groups.
                There was no evidence that offering women a 12-week standard exercise program during the second half of pregnancy prevents gestational diabetes or improves insulin resistance in healthy pregnant women with normal body mass indexes.
                : ClinicalTrials.gov, www.clinicaltrials.gov, NCT00476567. To examine the feasibility of an individualized exercise program to prevent gestational diabetes mellitus (GDM) in obese pregnant women.
                The study was a pilot randomized controlled trial with obese pregnant women (intervention group, individualized exercise program [n = 25]; control group, usual care [n = 25]). Average weekly energy expenditure (MET hours per week and kilocalories per week) of exercise-specific activity was assessed during pregnancy using the Pregnancy Physical Activity Questionnaire. Fasting glucose and insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed at baseline and 20, 28, and 36 weeks' gestation.
                Of the women in the intervention group, 16 of 22 (73%) achieved more than 900 kcal/week of exercise-based activity at 28 weeks compared with 8 of 19 women in the control group (42%), P = 0.047. However, insulin resistance (HOMA-IR) did not differ between the groups.
                This intervention was feasible and prompted a modest increase in physical activity. However, we are not confident that this intervention would be sufficient to prevent GDM.
There is limited randomised controlled trial evidence available on the effect of exercise during pregnancy for preventing pregnancy glucose intolerance or GDM. Results from three randomised trials with moderate risk of bias suggested no significant difference in GDM incidence between women receiving an additional exercise intervention and routine care.
Based on the limited data currently available, conclusive evidence is not available to guide practice. Larger, well-designed randomised trials, with standardised behavioural interventions are needed to assess the effects of exercise on preventing GDM and other adverse pregnancy outcomes including large-for-gestational age and perinatal mortality. Longer-term health outcomes for both women and their babies and health service costs should be included. Several such trials are in progress. We identified another seven trials which are ongoing and we will consider these for inclusion in the next update of this review.