Children of obese parents may suffer not only social stigma but actual developmental difficulties. The kids of obese mothers experienced significantly worse fine motor skills than their peers whose mothers had normal weight, report researchers at the U.S. National Institutes of Health. An obese father translated into significantly impaired social skills, and if both parents were obese, the children had a higher probability of failing problem-solving tests, the research showed.
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This new understanding could change the approach to helping young children who evince developmental delays, starting with the question of what their parents weigh.
By Israeli criteria, obesity is defined as having a body mass index (body weight divided by the square of the height), equal to or greater than 30. The Israeli Health Ministry flatly warns that obesity is a risk factor for chronic diseases, including diabetes, cardiac and vascular conditions, hypertension and even colon and uterine cancer. It also shortens the life span, the ministry observes.
Now it appears that it is also a risk factor for dysfunctional children, not just emotionally scarred ones.
A growing problem
The study, appearing in Pediatrics, was conducted by scientists at the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Lead author Edwina Yeung notes that most studies are confined to mothers. Not theirs: "Our results suggest that dad's weight also has significant influence on child development," she stated.
Obesity is a growing problem, so to speak: about 20% of pregnant women in the United States were overweight or obese as of the study – the figure for the UK is about the same, if not higher. (The rate in Israel is lower – in total, as of 2010, 15% of all Israeli adult women were obese, and they weren't all pregnant.)
Surveys done in Israel between the years 2007 and 2010 found that 35% of the population was overweight, with BMI scores between 25 and 30; and 15% was obese. In any case, the Health Ministry has been taking the rising rates of obesity in Israel seriously: among the measures proposed by Health Minister Yakov Litzman to combat the plague are banning junk foods and soda and candy vending machines from schools. He also took a swipe at McDonald's while about it.
Sins of the father
In the U.S. study, children were tested at four months of age and retested six more times through age three. When they enrolled, mothers also provided information on their health and weight before and after pregnancy, and the weight of their partners.
The differences were huge. Children of obese mothers were nearly 70 percent more likely to have failed the test indicator on fine motor skill by age 3 compared with peers born to normal-weight mothers, the researchers report.
Children of obese fathers were 75 percent more likely to fail the personal-social section of the test, which indicates how well they can relate to, and interact with, others by age 3.
Worst of all: Children with two obese parents were nearly three times more likely to fail the test's problem solving section by age 3.
Why parental obesity would impair development is not clear, but the answers seem to lie in the realm of real physiology. Obesity during pregnancy may promote inflammation, which could affect the fetal brain, based on animal studies – but that applies only to the mother.
The mechanism by which paternal avoirdupois affects behavioral development in the kids is unclear. The authors point at studies which indicate that obesity could affect not just fertility but the expression of genes in sperm (as demonstrated by this 2015 paper published by Physiological Reports, "Paternal obesity induces metabolic and sperm disturbances in male offspring that are exacerbated by their exposure to an 'obesogenic' diet").
True, that sperm study was done in mice. It categorically demonstrated that stuffing the murine father-to-be to the gills with fattening foods affected the ensuing sons. The male offspring of the obese mice had impaired the metabolic and reproductive health even if their own diets were controlled and normal (in other words, their problems were not caused by eating the same stuff being fed to their dads). So far the lesson is, if you have a breeding pair of mice, spare them the challah. But it could well be applicable to humans too.