Maternal BMI Biggest Indicator of Risk for Childhood Obesity

Becky McCall

June 03, 2019

Blood glucose levels that are elevated but below those associated with a diagnosis of gestational diabetes are associated with obesity risk in children, reinforcing the need for better management to reduce hyperglycemia in pregnancy, show findings from a study of over 45,000 women.

Compared with a normal blood glucose screening result, the risk of childhood obesity was a significantly higher among women with abnormal glucose screening (risk ratio [RR], 1.13; 95% CI, 1.06, 1.20), when adjusted for maternal age, race/ethnicity, and body mass index (BMI).

Researchers also found that having gestational diabetes did not significantly increase the risk of childhood obesity among normal weight or overweight women, but did do so among women with obesity.

The study, led by Samantha Ehrlich, PhD, professor of public health at the University of Tennessee, Knoxville, and fellow researchers at Kaiser Permanente Northern California, was published online May 10 in PLoS One.  

"This information is important because it suggests that we may be able to prevent childhood obesity in two ways: by helping mothers to achieve a normal BMI before they become pregnant and by reducing hyperglycemia during the pregnancy," said Ehrlich in a statement from her institution.

According to the authors, the findings also suggest that, in a clinical setting, an abnormal glucose screening test and/or a single abnormal value by International Association of the Diabetes and Pregnancy Study Groups (IADPSG) or Carpenter-Coustan (CC) thresholds could be used to identify infants at increased risk of childhood obesity.

However, they add, the prevalence of gestational diabetes would increase by at least 60.6% if a single abnormal value — by either threshold — were used for gestational diabetes diagnosis.

"The benefits of treating women meeting these lower thresholds must be considered alongside the increased burden on the healthcare system and cost of treatment," they note.

Large Database, More Than 45,000 Pregnant Women Studied

The researchers aimed to estimate the associations of various glucose criteria in pregnancy and thresholds recommended for the diagnosis of gestational diabetes with childhood obesity at 5 to 7 years of age.

In addition, they sought to investigate the joint effects of maternal BMI and pregnancy hyperglycemia on subsequent childhood obesity risk.

Data from over 46,396 pregnant women who delivered between 1995 and 2004 who were part of the Kaiser Permanente Northern California healthcare system were analyzed, and likewise the data (weight and height) of the resulting children, who were followed until 5 to 7 years of age.

Standard practice in the United States is for pregnant women to undergo a blood glucose screening test between gestational weeks 24 and 28. If the test shows elevated blood glucose levels, an additional test is then done to determine whether the woman has gestational diabetes.

Once elevated blood glucose levels were observed on a screening test (between week 24 and 28 of pregnancy), the resulting children had a higher risk of developing obesity between the ages of 5 to 7 years, even if blood glucose was below that deemed to be a diagnosis of gestational diabetes.

At a median of 6.3 years of age, 4900 children (10.6%) were classified as obese according to International Obesity Task Force cut-offs and 7360 (15.9%) were obese according to US Centers for Disease Control and Prevention growth standards.

Maternal BMI: Most Modifiable Factor to Prevent Obesity in Offspring

Ehrlich and coauthors stress, however, that the association between hyperglycemia during pregnancy and childhood obesity is in large part explained by maternal BMI.

"Examination of the joint impact of maternal BMI and GDM [gestational diabetes] revealed that GDM may only compound the risk of childhood obesity in women with obesity," Ehrlich explains in the press release.

In obese women with gestational diabetes (compared to obese women without GDM), risk of childhood obesity was significantly increased by 20% (RR, 1.20; 95% CI, 1.07, 1.34).

However, add the researchers, gestational diabetes per se did not significantly increase the risk of childhood obesity among normal weight (RR, 1.15; 95%: CI 0.88, 1.52) or overweight women (RR, 1.15; 95% CI, 0.97, 1.37).

"Taken together, the results of this study suggest that maternal BMI may be the more salient, modifiable risk factor for childhood obesity than GDM," the authors conclude.  

The authors have reported no relevant financial relationships.

PLoS One. Published online May 10, 2019. Full text

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