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Exercise program ineffective in preventing gestational diabetes, reports study

Robin Wulffson MD's picture
gestational diabetes, exercise, obesity, weight loss, pregnancy outcome

Exercise programs have been reported to facilitate weight loss; thus, reducing the incidence of type 2 diabetes. It is a reasonable assumption that such programs would reduce the incidence of gestational diabetes; however, a new study reported that an exercise program was ineffective against gestational diabetes.

The findings were published by researchers in The Netherlands online ahead of print on May 23 in BJOG: An International Journal of Obstetrics and Gynaecology.

The authors designed a program to evaluate the effectiveness of an exercise program for pregnant women who were overweight or obese and at risk for gestational diabetes. From 2007 through 2011, pregnant women who were overweight or obese and at risk for diabetes mellitus were recruited for the study. The study group was comprised of 121 women who were randomly assigned to either a control group (59 women) or an intervention group (62 women). Normal prenatal care was compared with an exercise training program during pregnancy. The training consisted of aerobic and strength exercises, and was aimed at improving maternal fasting blood glucose, insulin sensitivity, and birth weight.

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Maternal outcome measures were fasting blood glucose (mmol/l), fasting insulin (pmol/l). and HbA1c (%), body weight (kg), body mass index (kg/m2), and daily physical activity (minutes/week). Newborn outcome measures were birth weight and fetal growth. The researcher found that the exercise program did not reduce either maternal fasting blood glucose levels or insulin sensitivity. Furthermore, no effect was found on birth weight. (Women with gestational diabetes are prone to deliver macrosomic (large for gestational age) infants.)

Up to 24 weeks' of pregnancy, 33% of the women in the exercise group attended at least half of the exercise sessions; however, from 24 weeks onward, only 11% did so. Overall, only 16% attended at least half of the exercise sessions throughout their pregnancy; the authors noted that this group was too small for per protocol analyses. At baseline, the women in the intervention group were spending an average of 202 minutes doing moderate to vigorous physical activity each week; the control group women were spending 218 minutes. At 32 weeks' gestation, the average time spent in moderate to vigorous activity per week was 151 minutes for the intervention group and 178 minutes for the control group. The authors noted that neither difference was statistically significant.

The authors concluded that an exercise program conducted over the second and third trimester of pregnancy had no effects on fasting blood glucose, insulin sensitivity, and birth weight. They theorized that this was probably due to low compliance. They noted that the high prevalence of women at risk for gestational diabetes calls for further research on possible interventions that can prevent the condition as well as other types of interventions to engage this target group in physical activity and exercise.

Take home message:
I was surprised to note the conclusions of this study until I absorbed the words: “low compliance.” Thus, this study is a sad testimonial that overweight women are poorly motivated to improve their health through a diet and exercise program. Women who are not overweight before or during a pregnancy have an increased chance of a good outcome for themselves as well as their fetus. Moderate exercise is beneficial to all women—whether or not they are pregnant. Joints are more elastic during pregnancy; thus, they are more susceptible to injury. Balance is impaired, which increases the risk of falling. High impact exercise, which strains joints should be avoided. Also activities with any risk of falling should be avoided. A sports bra should be worn during pregnancy to provide support to the enlarged breasts; thus, avoiding tissue breakdown.

Reference: BJOG: An International Journal of Obstetrics and Gynaecology