Exceed exercise guidelines to prevent gestational diabetes

Current pregnancy guidelines recommend that most pregnant women perform at least 30 minutes of moderate exercise "most days of the week" unless there are clinical reasons to avoid it. In addition to the reasons to exercise for those who are not pregnant, regular, moderate exercise may help the pregnant person avoid excessive pregnancy weight gain, decrease constipation, and may (anecdotally) help with the hard work of labor itself.

More critically, previous research has suggested that those women who exercise regularly in the first half of their pregnancy (the first 20 weeks) cut their risk of gestational diabetes nearly in half. Today's research looks at those guidelines more closely (Diab Care 2021;44:425-432).

Pregnant persons receiving prenatal care at Kaiser Permanente of Northern California were invited to participate in a prospective study known as PETALS (Pregnancy Environment and Lifestyle Study). This cohort study began in 2013; participants were invited to join the study before the 11th week of their pregnancy.

As you might expect, the participants responded to demographic and dietary questionnaires. In addition, specifically for this study the participants filled out a Pregnancy Physical Activity Questionnaire (PPAQ), which asked the pregnant person to estimate the time they spent in 36 pregnancy-appropriate activities within the previous 2 months. The amounts of time spent were grouped in increasing levels: none; less than 1/2 hour per day, between 1/2 and 1 hours per day, etc., up to more than 3 hours per day.

The Physical Activity measure was specifically designed to record activities "other than ... household tasks," or rather, "[physical activity] that is intentional for health and wellness."

The authors of this study recognized that self-reported levels of physical activity might not be the most accurate measures. Instead of breaking out the levels of activity as incrementally as the questionnaire, they grouped the levels of activity more broadly: Did they (or did they not) meet the current guidelines for physical activity (the equivalent of at least 150 minutes per week - or 22.5 minutes per day - of moderate exercise)?

A significant percentage of participants exercised more than the minimum guidelines, however, so the authors set another, higher comparative threshold of at least 264 minutes per week of moderate exercise (about 38 minutes per day, on average).

The authors excluded those women who were instructed against exercise by their physicians, who did not receive a glucose challenge test (the test indicating gestational diabetes) between 24 and 28 weeks of their pregnancy, and those whose records of physical activity were somehow implausible, leaving 2,501 persons who gave birth between October 2013 and October 2017.

Fifty-six percent of the pregnant persons were clinically overweight or obese in early pregnancy, and just over 40% reported exercising in amounts meeting or exceeding the physical activity guidelines.

The authors found that those whose level of exercise met only the minimum level of 150 minutes of moderate-intensity exercise per week did not see any reduction in their risk of gestational diabetes. On the other hand, those whose level of excercise was at least 264 minutes per week of moderate-intensity exercise reduced their risk of gestational diabetes by about 32%.

What this means for you

Gestational diabetes poses significant risks to both pregnant parent and child (more here) in the short term as well as increasing their risk of obesity and diabetes. The good news is that you don't have to spend the money on a fitness center membership to get enough moderate-intensity exercise: a good example is brisk walking, or at about a 4 mile-per-hour pace (2 miles in 30 minutes).

First posted: April 7, 2021