Most of these studies focused their attention on the impacts of the mothers’ health and habits, though. Less has been known about how a father’s metabolic health changes his children’s long-term metabolic prospects and whether a mother’s activities during pregnancy might counter any negative outcomes from a father’s way of life.
So, for the new study, which was published in March in the Journal of Applied Physiology, scientists at the University of Virginia School of Medicine and other institutions first gathered a large group of mice. Some of the animals, male and female, were allowed to gorge on a high-fat, high-calorie diet, inducing obesity and metabolic problems, while others remained on normal chow, at their usual weight.
Next, the mice hooked up, with obese animals of both genders mating with normal-weight mice, so that, in theory, one parent in each pairing could bequeath unhealthy habits and metabolism to the young. A few normal-weight animals without metabolic problems also mated, to produce control offspring.
Finally, some mothers, including the obese, jogged on little running wheels throughout the resulting pregnancies, voluntarily covering up to 7 miles (11.26 kilometres) a week in the early stages of their three-week gestations.
Afterward, the researchers tracked the metabolic health and underlying genetic activity of the offspring, until they reached adulthood. This second generation ate normal chow and led normal, lab-mouse lives.
Many, though, developed multiple metabolic problems as adults, including obesity, insulin resistance and other disruptions of their blood-sugar control. These conditions were most pronounced in the male children of obese mothers and in both the male and female children born to obese fathers.
Interestingly, the underlying genetics of their conditions differed by parental gender. Mice born to obese mothers displayed unusual activity in a set of genes known to be involved in inflammation. Those born to obese fathers did not.
In other words, the genetic legacies from mothers and fathers “operate through different biological pathways,” says Zhen Yan, a professor of medicine and director of the Center for Skeletal Muscle Research at the University of Virginia School of Medicine, who oversaw the new study.
Perhaps most important, though, when the mothers ran during pregnancy, their children showed almost no undesirable metabolic outcomes as adults, whether the mother or father was obese. These offspring, metabolically and genetically, remained indistinguishable from animals born to healthy parents.
Of course, this was a rodent study and we are not mice, so it is impossible to know if we — as mothers, fathers or offspring — respond similarly to diets and exercise, or if the effects are amplified when both parents are affected. The study also does not show if it is obesity or a high-fat diet that most drives intergenerational harms or what the ideal timing, types and amounts of exercise might be by either mum or dad, to combat those effects.
Yan says he and his colleagues plan to investigate those questions in future experiments. But already, the current study and other research suggest, he says, that physical activity, before and during pregnancy, and by both the expectant mother and father, “should absolutely be encouraged.”
The New York Times
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