A healthier diet reduces the risk of pregnancy complications

In 2021 we reported on a study that suggests that those women who exercise more than the current guidelines recommend - about 264 minutes per week as opposed to 150 minutes per week - were 32% less likely to develop gestational diabetes, an illness that can lead to serious complications for both mother and child.

Today's research, published in the American Journal of Clinical Nutrition (2021;0:1-9), looks at the risks of common pregnancy complications, from gestation diabetes to hypertension and eclampsia, within the context of the pregnant person's usual diet before or in early pregnancy.

Between 2009 and 2013, 12 clinical centers across the United States cooperated to recruit over 2800 persons who were between 8 and 13 weeks pregnant to participate in an observational study that lasted through their child's delivery.

Those expectant mothers who had a history of pregnancy complications, a history of high blood pressure or diabetes, or those who had other lifestyle risk facts such as smoking or drinking alcohol were excluded from the study, as were those who did not respond to at least one of three dietary questionnaires. These were administered upon enrollment, at 16 weeks gestation, and at 24 weeks gestation. Thus 1887 women were included in the final analysis.

The authors compared the participants' diets to three different healthy dietary patterns: the Alternate Healthy Eating Index (AHEI), which measures adherence to the 2005 Dietary Guidelines for Americans; the Alternate Mediterranean Diet (AMD) an alternate scoring of the standard Mediterranean Diet, and the DASH diet (Dietary Approaches to Reduce Hypertension). As alcohol is discouraged during pregnancy, it was not included in the scoring for the AHEI or the AMD.

In their analysis comparing the diets of those women experiencing complications such as gestational diabetes, high blood pressure, pre-eclampsia, and pre-term delivery to those who gave birth without such complications, the authors took into account the participants' pre-pregnancy Body Mass Index, overall caloric intake, physical activity, maternal age, ethnicity, and family health history.

While previous research has produced varied results with respect to which diet reduced the risk of which complication the most, here the authors summarize their findings thus: "Healthier diet characterized by higher AHEI, AMED, or DASH scores was independently associated with lower risks of pregnancy complications in general."

For example, those women with an AHEI score in the top 25% were 68% less likely to develop gestational diabetes, while a DASH score in the top 25% meant a 65% lower risk of high blood pressure and an AHEI score in the top 25% meant a 69% lower risk of preeclampsia. Scores were similar across all three healthy diets, and the results didn't appear to be affected by whether the participants had previously given birth or whether their Body Mass Index before getting pregnant was clinically normal, overweight, or obese.

What this means for you

The authors caution that this is a comparatively small study and that dietary recalls are notoriously subject to error. Further, as the participants were assessed after they knew they were pregnant, it's possible that they altered their usual diet in light of that news.

Nevertheless, this is in line with other studies that suggest that an overall healthy diet that's high in fruits, vegetables, and whole grains, with leaner meats, more fish, and less highly processed foods will help ensure a safer, healthier pregnancy - and likely a healthier baby.

First posted: July 6, 2021