Pregnant women who exercise more during the first trimester of pregnancy may have a lower risk of developing gestational diabetes, according to a study led by Samantha Ehrlich, an assistant professor in the department of public health at the University of Tennessee-Knoxville, and adjunct investigator with the Kaiser Permanente Division of Research. The analysis found that lower risk was associated with at least 38 minutes of moderate intensity exercise each day – a bit more than current recommendations of at least 30 minutes a day five days a week.
Gestational diabetes refers to diabetes diagnosed for the first-time during pregnancy. It can pose serious health problems including pregnancy and delivery complications as well as increased future risk for diabetes in both mother and child.
Ehrlich said, "We know that exercise is safe and beneficial for healthy pregnant women. These results show that exercise is helpful in avoiding gestational diabetes, though you might need to do a little bit more than currently recommended to enjoy that benefit."
The observational study was based on women's self-reported levels of exercise during their first trimester of pregnancy. It found that exercising at least 38 minutes per day lowered the risk of gestational diabetes by 2.1 cases per 100 women and the risk of abnormal blood sugar by 4.8 cases per 100 women.
"We know that six to 10 women per 100 get gestational diabetes," Ehrlich said. "If being more active could reduce that by two women per 100, that's a clear benefit."
The study analyses data collected for the Pregnancy Environment and Lifestyle Study (PETALS), a longitudinal study that included a physical activity questionnaire from 2,246 pregnant members of Kaiser Permanente Northern California. The women in the study were racially and ethnically diverse and of a wide range of pre-pregnancy weight classifications.
The authors suggest that the current recommendations may need to be rethought to improve women's chances of preventing gestational diabetes with exercise. The most recent guidelines from the American College of Obstetricians and Gynaecologists were updated in 2020, and those from the US Department of Health and Human Services were updated in 2018.
Exercise During the First Trimester of Pregnancy and the Risks of Abnormal Screening and Gestational Diabetes Mellitus
Samantha F Ehrlich, Assiamira Ferrara, Monique M Hedderson, Juanran Feng, Romain Neugebauer
Published in Diabetes Care in 21 December 2020
To estimate the effects of exercise during the first trimester on the risks of abnormal screening and gestational diabetes mellitus (GDM).
Research and Design and Methods
Data come from PETALS, a prospectively followed pregnancy cohort (n = 2,246, 79% minorities) receiving care at Kaiser Permanente Northern California. A Pregnancy Physical Activity Questionnaire was used to assess exercise. Glucose testing results for screening and diagnostic tests were obtained from electronic health records. Inverse probability of treatment weighting and targeted maximum likelihood with data-adaptive estimation (machine learning) of propensity scores and outcome regressions were used to obtain causal risk differences adjusted for potential confounders, including prepregnancy BMI, exercise before pregnancy, and gestational weight gain. Exercise was dichotomized at 1) the cohort’s 75th percentile for moderate- to vigorous-intensity exercise (≥13.2 MET-h per week or ≥264 min per week of moderate exercise), 2) current recommendations (≥7.5 MET-hours per week or ≥150 min per week of moderate exercise), and 3) any vigorous exercise.
Overall, 24.3% and 6.5% had abnormal screening and GDM, respectively. Exercise meeting or exceeding the 75th percentile decreased the risks of abnormal screening and GDM by 4.8 (95% CI 1.1, 8.5) and 2.1 (0.2, 4.1) fewer cases per 100, respectively, in adjusted analyses.
Exercise reduces the risks of abnormal screening and GDM, but the amount needed to achieve these risk reductions is likely higher than current recommendations. Future interventions may consider promoting ≥38 min per day of moderate-intensity exercise to prevent GDM.
University of Tennessee at Knoxville material
Diabetes Care study (subscription required)
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