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A plant-forward diet prevents gestational diabetes

In 2014 Faith Bontrager, our pregnancy columnist, reported on a study that showed that the more closely a pregnant person's diet matched a Mediterranean-style diet, the less likely they were to develop gestational diabetes, a potentially serious complication for both parent and child.

The British Journal of Nutrition recently published a study of women in China that looks not at a Mediterranean-style diet but rather what they term a plant-based diet and its effects on the risk of gestational diabetes (2021; doi:10.1017/S0007114521000234).

The authors used data gathered for the Tongji Maternal and Child Health Cohort (TMCHC), a prospective study of pregnant women and their children living in a province in central China. The participating women were recruited at their first prenatal visit at the participating hospital between January 2013 and May 2016.

The participants completed a dietary questionnaire specifically based on common Chinese food items and Chinese eating habits. The questionnaire was broken into 12 food groups, 8 plant-based and 4 animal-based.

The amount of food consumed of each food group was classified into 5 levels of intake: those who consumed the amount in the top 20% of intake received a score of 5 (for plant-based foods) or 1 (for animal-based foods). The second-highest 20% of intake received a 4 (for plant-based foods) or 2 (for animal-based foods, and so on. Thus a higher score meant consuming the greatest amount of plant-based foods and the least of animal-based foods: the lowest possible score was 12 and the highest, 60. The highest score any participant received was 52, and the lowest was 21.

The authors limited their analysis to those women who delivered only a single child (not twins, for example), who had not had gestational diabetes in a previous pregnancy, and those who had not been diagnosed with diabetes.

Of the nearly 2,100 women included in the study, 169 were diagnosed with gestational diabetes. They tended to be older, have a higher pre-pregnancy Body Mass Index as well as more weight gain during the pregnancy, and did not exercise in their leisure time as much as those who were not diagnosed with gestational diabetes.

Compared to those with a plant-based diet score between 21 and 33, those with a plant-based diet score between 40 and 52 were 37% less likely to develop gestational diabetes, even after taking into account total calories consumed, pre-pregnancy Body Mass Index, family history of diabetes, education, and other factors.

Those whose score was between 37 and 39 saw their risk fall by 24%, and those with a score of 34-36 still reduced their risk by 13%.

The authors note that the percentage of women in this study who were diagnosed with gestational diabetes is lower than the average in China: 8% as opposed to 14.8% countrywide. Further, the participants in the study tended to be younger and have a lower pre-pregnancy BMI than other areas in China. Thus they caution that "the generalisability of our findings to general populations may be limited."

What this means for you

It's important to note that a "plant-based diet" in this context does not necessarily mean vegan (no animal products whatsoever) or even vegetarian. It might be more helpful to think of this as a plant-forward diet: these women were still eating meat, after all. A Mediterranean-style diet is a plant-forward (or plant-based) diet, and this study adds to the evidence that a Mediterranean-style diet is a healthy diet, before, during, and after pregnancy.

First posted: March 10, 2021