Metabolic health of pregnant women may matter more than weight gain

Metabolic health before and during pregnancy may have a bigger influence on risks for mother and baby than simply controlling weight gain. Data from a recent paper by Pennington Biomedical researchers indicates that pregnant women with metabolically unhealthy obesity were more likely to develop gestational diabetes than those who were metabolically healthy.

The paper, “Metabolic Health and Heterogenous Outcomes of Prenatal Interventions: A Secondary Analysis of a Randomized Clinical Trial,” is published in JAMA Network Open.

In the “Lifestyle Interventions for Expectant Moms” trial, which informed the paper, researchers evaluated the effect of prenatal lifestyle interventions on gestational weight gain in mothers with overweight and obesity. In the current analysis, the authors evaluated expectant mothers with metabolically healthy obesity, which is obesity without major metabolic risk factors, and those with metabolically unhealthy obesity, which is obesity with at least two metabolic risk factors, such as high blood sugar, high blood pressure or cholesterol.

They found that women with metabolically unhealthy obesity gained less weight during pregnancy than those with metabolically healthy obesity. Regardless of the weight gain differences, women with metabolically unhealthy obesity had more cases of gestational diabetes and their infants had more body fat.

“Traditionally, we’ve placed a strong emphasis on weight gain during pregnancy, since excessive weight gain is linked to adverse outcomes for both mother and baby,” said Dr. Emily Flanagan, researcher and Director of the Developmental Physiology lab at Pennington Biomedical.

“But the fetus doesn’t ‘sense’ weight; instead, it grows based on metabolic substrates like glucose and lipids, which tend to be elevated with obesity. These findings challenge the long-standing assumption that managing gestational weight gain alone is enough. Instead, we need to shift our focus toward early interventions that help regulate maternal glucose and lipid levels to truly improve the health outcomes of a mother and her baby.”

When comparing metabolically healthy and metabolically unhealthy participants, the researchers found that the metabolically unhealthy participants gained nearly 37% less weight but were twice as likely to develop gestational diabetes. Of the 400 participants with obesity evaluated, 24% of those with metabolically unhealthy obesity developed gestational diabetes, compared to 10% of those with metabolically healthy obesity.

“We take great pride in our unwavering dedication to enhancing nutrition and metabolic wellness throughout every stage of life, with special focus on supporting mothers-to-be,” said Dr. John Kirwan, Executive Director of Pennington Biomedical. “This outstanding research by Dr. Emily Flanagan, Dr. Leanne Redman, Dr. Kimberly Drews and their talented team beautifully exemplifies our mission in action, revealing exciting opportunities to boost metabolic health for expectant mothers both before conception and throughout their pregnancy journey.”

The study included lifestyle interventions, of which both groups—those with metabolically healthy obesity and metabolically unhealthy obesity—had the intervention initiated toward the end of the first trimester and responded similarly. This study indicates that an earlier intervention that is specifically tailored to improving metabolic health, rather than controlling weight gain alone, may have helped to reduce the prolonged elevated exposure of glucose and lipids to the fetus, especially in mothers who have elevated substrates at the start of pregnancy.