Clinical Context

Childhood obesity increases risk for cardiovascular disease, diabetes, cancer, and premature death and is rising at alarming rates in the US.

Ultraprocessed foods are common in contemporary Western style diets, constitute more than half of all energy intake among US youth, and are linked to weight gain, excess body fat, overweight, and obesity in adults and children. Transgenerational associations between maternal consumption of ultraprocessed foods and offspring body weight are still unidentified.

Study Synopsis and Perspective

A mother's consumption of ultraprocessed foods appears to be related to an increased risk for overweight or obesity in her children, according to new research.

Among the 19,958 mother-child pairs studied, 12.4% of children developed obesity or overweight in the full analytic study group, and the offspring of those mothers who ate the most ultraprocessed foods (12.1 servings/day) had a 26% higher risk for obesity/overweight compared with those with the lowest consumption (3.4 servings/day), report Andrew T. Chan, MD, MPH, professor of medicine at Harvard Medical School in Boston, Massachusetts, and colleagues.

This study demonstrates the possible advantages of restricting ultraprocessed food consumption among women and mothers who are in their reproductive years to potentially lower the risk for childhood obesity, the investigators note.

"These data support the importance of refining dietary recommendations and the development of programs to improve nutrition for women of reproductive age to promote offspring health," they write in their article, published in BMJ.

"As a medical and public health community, we have to understand that the period of time in which a woman is carrying a child or during the time when she is raising her children represents a unique opportunity to potentially intervene to affect both the health of the mother and also the health of the children," Dr Chan told Medscape Medical News in an interview.

It is important to address these trends both on an individual clinician level and on a societal level, noted Dr Chan.

"This is a good opportunity to counsel patients about the potential linkage between their consumption of ultraprocessed food for not just themselves but also their kids, and I think that added counseling and awareness may motivate individuals to think about their diets in a more favorable way," he added.

Ultraprocessed foods are affordable and convenient, and many communities are not able to easily access fresh and healthy foods, so "it is incumbent upon [clinicians] to make it a priority and to break down those social and economic barriers, which make it difficult to have healthy and less processed food," Dr Chan elaborated.

Modern Western diets frequently include ultraprocessed foods, such as packaged baked goods and snacks, fizzy drinks, and sugary cereals, which are linked to adult weight increase. The relationship between parental consumption of highly processed meals and offspring weight is, however, unclear across generations, the researchers note.

Hence, they set out to determine whether eating ultraprocessed foods during peri-pregnancy and while raising children increased the risk for being overweight or having obesity among children and teenagers.

The study team assessed 14,553 mothers and their 19,958 children from the Growing Up Today Study (GUTS I and II) and Nurses' Health Study II (NHS II) in the United States. Males accounted for 45% of the children in the study, and the children's ages ranged from 7 to 17 years.

The NHS II is a continuing investigation following the lifestyle and health choices of more than 100,000 female registered nurses in the United States in 1989, whereas the GUTS I involved about 17,000 children of the nurses in the NHS II. Participants in GUTS I filled out an initial lifestyle and health survey and were evaluated annually between 1997 and 2001 and every 2 years thereafter. 

Roughly 11,000 children from the NHS II were included in the GUTS II. The children were further evaluated in 2006, 2008, and 2011, as well as every 2 years thereafter.

Participants were followed until the children reached 18 years of age or experienced obesity and overweight onset. A subcohort consisted of 2925 mother-child pairs with data on peripregnancy eating patterns.

Maternal intake of ultraprocessed foods while raising children was linked to obesity or overweight in children. Moreover, compared with the lowest-consumption cohort (3.4 servings/day), there was a 26% greater risk for the greatest maternal ultraprocessed food intake cohort (12.1 servings/day), after adjusting for child's sedentary time, ultraprocessed food intake, physical activity, and established maternal risk factors.

Even though rates were elevated, ultraprocessed food intake during pregnancy was not significantly linked to a higher risk for obesity or overweight in children (P _{for trend}=.07).

Sex, birth weight, age, gestational age, or maternal body weight had no effect on these correlations either.

The study's limitations include the fact that some of the children in the pairs were lost during follow-up and there may have been data misreporting, as the weight and diet measures were provided via self-reported questionnaires, and potential residual confounding, given the observational study design, the researchers note.

Other limitations include that the mothers involved in the study came from similar socioeconomic backgrounds, had similar personal and familial educational statuses, and were primarily White, which limits the generalizability of these data to other ethnic groups, the authors add.

"Further studies are warranted to investigate specific biological mechanisms and socioeconomic determinants underlying the observed associations between maternal ultra-processed food intake and offspring [overweight] and obesity," the researchers conclude.

BMJ 2022;379:e071767.^[1]

Study Highlights

• Participants in this US population-based prospective cohort study were 19,958 mother-child pairs from NHSII, GUTS I and II (45% boys; age 7-17 at enrollment).
• A subsample of 2925 mother-child pairs had peripregnancy diet information.
• Median follow-up was 4 years (interquartile range, 2-5 years) until age 18 or overweight or obesity onset.
• Multivariable adjusted, log binomial models with generalized estimating equations and exchangeable correlation structure accounted for correlations between siblings and estimated relative risk for offspring overweight or obesity.
• In the full cohort, 2471 (12.4%) offspring developed overweight or obesity.
• As maternal ultraprocessed food consumption increased, maternal intake of carbohydrates, trans fatty acids, and sodium increased, whereas maternal protein intake and overall diet quality decreased.
• As maternal ultraprocessed food consumption increased, offspring's consumption of ultraprocessed foods also increased (P<.001) and overall diet quality decreased.
• Maternal consumption of ultraprocessed foods during childrearing was associated with overweight or obesity in offspring, after adjustment for established maternal risk factors and offspring's ultraprocessed food intake, physical activity, and sedentary time.
• Risk was 26% higher in the group with highest maternal ultraprocessed food consumption (12.1 servings/day) vs lowest consumption (3.4 servings/day; RR, 1.26, 95% CI: 1.08-1.47; P for trend<.001).
• Among subtypes of ultraprocessed foods, ultraprocessed breads and breakfast foods were independently associated with childhood risk for overweight or obesity (relative risk per 1 SD increase, 1.10; 95% CI, 1.06-1.15).

Figure. Effect of High Maternal Consumption of Ultraprocessed Food During Child Rearing

• In the subsample with peripregnancy diet information, rates were higher, but peripregnancy ultraprocessed food intake was not significantly linked to greater risk for offspring overweight or obesity (n=845 [28.9%]; highest vs lowest intake RR, 1.17; 95% CI, 0.89-1.53; P for trend=.07).
• Age, sex, birth weight, and gestational age of offspring or maternal body weight did not modify these associations.
• The investigators concluded that maternal consumption of ultraprocessed food during the childrearing period was linked to increased risk for offspring overweight or obesity in during childhood and adolescence, independent of maternal and offspring lifestyle risk factors.
• They recommend further study to confirm these findings and clarify underlying biological mechanisms and environmental and socioeconomic determinants.
• Potential mechanisms may include maternal diet during childrearing shaping offspring's diet and lifestyle choices, long-term in utero imprinting, and the presence of uncharacterized gene-by-environment factors.
• Potential mechanisms by which peripregnancy ultraprocessed food intake could affect offspring adiposity include epigenetic modification of offspring's susceptibility to obesity, as maternal poor diet quality may affect genes involved in the regulation of growth, energy balance, and insulin resistance in offspring.
• Proinflammatory additives in ultraprocessed foods may also cause chronic maternal inflammation, which has been linked to increased offspring adiposity.
• The findings support the need to refine dietary recommendations, including limiting ultraprocessed food consumption, and to develop programs to improve nutrition for women of reproductive age to promote offspring health.
• Social determinants of health may hinder women from reducing ultraprocessed food intake, including insufficient time to prepare unprocessed food; additional costs of a healthier diet, including limited shelf life that might result in greater waste; mothers not being solely responsible for household foods; and limited access to healthy food options in some geographical locations.
• As many women may already experience shame for weight-related health behaviors during pregnancy and childrearing, these findings should not be used to further stigmatize their food choices.
• Addressing these financial and social structural barriers to making healthy food choices is essential to developing achievable, responsible dietary guidelines for women of childbearing age.
• Study limitations include some children lost to follow-up; reliance on self-reported weight and diet measures, observational design with potential residual confounding, and limited generalizability to non-White populations.

Clinical Implications

• Maternal consumption of ultraprocessed food during childrearing was linked to increased risk for overweight or obesity in offspring.
• Further study is needed to clarify the underlying biological mechanisms and environmental and socioeconomic determinants of health.

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