Healthy Lifestyle Among Mothers Significantly Impacts Child's Risk of Obesity

Klodian Dhana, MD, PhD, MSc, DSc

Mothers that maintain a healthy lifestyle during their offspring's childhood can have a significant impact on their children’s risk of obesity, according to new research.

While it is already known that adherence to an overall healthy lifestyle is linked to a substantially reduced risk of multiple poor health outcomes, including type 2 diabetes, coronary heart disease, and mortality, it was unknown if these benefits affected offspring. While obesity has become a major issue among children and adolescents in the United States—20% of children aged 6 to 19 years are obese—the findings suggest that implementing family or parental-based interventions could have an impact on the rise of childhood obesity.

"Through research over the years, we have shown that women who adhere to an overall healthy lifestyle have a substantially reduced risk of chronic diseases and mortality," lead author Klodian Dhana, MD, PhD, MSc, DSc, told MD Mag. "Our study demonstrated a 75% decrease in obesity risk in offsprings when the mothers followed five healthy habits in combination—characterized by a healthy body mass index, high-quality diet, regular exercise, no smoking, and light to moderate alcohol intake. Clinicians should be informed about the importance of mothers’ lifestyle during the period of their offspring’s childhood and adolescence because it was critical to the risk of obesity in their children, as shown in our study."

In order to examine this association between the factors making up a healthy lifestyle, defined as a healthy body mass index (BMI), a high-quality diet, regular exercise, a light-to-moderate alcohol intake, and a lack of smoking, and the risk for the development of childhood obesity, the authors, led by Dhana, a research fellow at the T.H. Chan School of Public Health at Harvard University, examined the medical histories and lifestyle characteristics of 24,289 children aged 9 to 14 years (mean age, 12 years; 45.8% male, n = 11,133), born to 16,945 mothers in 2 studies, the Nurses' Health Study II (NHSII) and Growing Up Today Study (GUTS).

Obesity was defined using the parameters set by the International Obesity Task Force, while the risk of the condition was assessed with multivariable log-binomial regression models with generalized estimating equations and an exchangeable correlation structure. In total, 5.3% of the offspring (n = 1282) became obese over the mean 5-year follow-up.

For those whose mothers kept up a healthy BMI between 18.5 and 24.9, the relative risk of obesity was 0.44 (95% CI, 0.39 to 0.50). Comparatively, those with mothers who had a BMI of ≥30 had a relative risk of 3.10 (95% CI, 2.69 to 3.57). Likewise, the relative risk was lower for those whose mothers were not smokers (0.69; 95% CI, 0.56 to 0.86) than those that were current (1.55; 95% CI, 1.25 to 1.92) or former (1.16; 95% CI, 1.01 to 1.33) smokers.

Additionally, mothers who engaged in 300 minutes per week of moderate to vigorous physical activities had children with a relative risk of developing obesity of 0.73 (95% CI, 0.57 to 0.94). Those who exercised with the same vigor for 150 to 299 minutes per week reduced their child’s relative risk to 0.58 (95% CI, 0.46 to 0.74).

With regard to the consumption of alcohol, those with mothers that did so in moderation, defined as 1.0 to 14.9 g/day, had a relative risk of obesity of 0.88 (95% CI, 0.79 to 0.99). Specifically, light consumption (1.0 to 4.9 g/day) resulted in a relative risk of 0.89 (95% CI, 0.78 to 1.01), and moderate consumption (5.0 to 14.9 g/day) resulted in a relative risk of 0.80 (95% CI, 0.67 to 0.96).

Although when it came to diet, as measured by Alternate Healthy Eating Index 2010 diet score, Dhana and colleagues wrote that, “when we compared the top and bottom 20% groups of the Alternate Healthy Eating Index 2010 diet score, the relative risk was 0.99 (0.82 to 1.19).”

"Unexpectedly, in our study, mothers' dietary pattern was not associated with offspring obesity, possibly because children's diets are affected by multiple factors including school and neighborhood food environments and peer influences.,” Dhana said.

When all healthy lifestyle factors were considered simultaneously, offspring of women who adhered to all 5 low-risk lifestyle factors reduced their children’s risk of obesity by 75% more than those whose mothers did not exercise any of the low-risk factors (relative risk, 0.25; 95% CI, 0.14 to 0.47).

“This association was similar across sex and age groups and persisted in subgroups of children with various risk profiles defined by factors such as pregnancy complications, birth weight, gestational age, and gestational weight gain,” the authors wrote. “Children’s lifestyle did not significantly account for the association between maternal lifestyle and offspring obesity risk, but when both mothers and offspring adhered to a healthy lifestyle, the risk of developing obesity fell further (0.18, 0.09 to 0.37).”

As the study revealed that the mother’s lifestyle was more impactful on childhood obesity than the child’s lifestyle, Dhana and colleagues noted that there are several factors that could have played a role in this weak mediation effect. First, that the limitations of the collectible data on the aspects of the children’s lifestyle, such as exposure to secondhand smoke. They also noted that measurement errors may have had an effect, due to the analysis’ self-reported nature, as the accuracy of children’s self-reported measurements has not been as validated as those of adults.

“Overall, these methodological limitations could partly explain the weak influence of offspring lifestyle on the associations between maternal lifestyle and offspring obesity. Moreover, the etiology of childhood obesity is complicated and could involve a network of diet, behaviors, psychosocial determinants, and other factors,” Dhana and colleagues wrote. “It is likely that mothers’ lifestyle might exert effects on childhood obesity risk through pathways other than children’s lifestyle, although more research is needed in this regard.”

"Adherence to a healthy lifestyle should be encouraged in both mothers and their children, as our results revealed a further reduction in the risk of offspring obesity," Dhana said. "This research lends support to family or parent based intervention strategies for reducing childhood obesity risk."

The study, “Association between maternal adherence to healthy lifestyle practices and risk of obesity in offspring: results from two prospective cohort studies of mother-child pairs in the United States,” was published in The BMJ.