Of the many powers mothers wield, few are more extraordinary than the power to nudge a child’s health prospects in one direction or another simply by having incubated that child in her womb. Research is uncovering more and more instances in which a pregnant woman’s own health issues powerfully influence those of her child. A new study demonstrates this is especially true of her weight status, and shows that weight-loss surgery can change the picture dramatically.
Research has already shown that the children that obese women bear before and after they have undergone bariatric surgery are different from each other. Compared with their peers born to obese women, children born to mothers following weight-loss surgery are significantly less likely to be obese. They have healthier blood pressure, lipid profiles and metabolic function.
A new study, published this week in the journal Proceedings of the National Academy of Sciences (PNAS), makes clear that weight-loss surgery does much more than change the example a mother sets for her child, or the consumption patterns she passes on at the high chair and the dinner table. Looking at groups of siblings — children born to the same woman before and after she has undergone weight-loss surgery — Canadian researchers found significant differences in the way genes influencing weight, metabolic function and inflammation express themselves.
The phenomenon is called “fetal programming.” A woman’s nutrition, her stress levels, her exposure to toxic pollutants and her own health status can bend a baby’s genetic make-up not by changing the code, but by tweaking the way those genes carry out their program.
The researchers rounded up 20 mothers who had undergone gastric bypass surgery, and 50 of the womens’ children became their subjects. Half of the subjects were born before their mother’s surgery and half were born after. The average age of the kids born to heavier mothers was almost 15 years old; the children born after their mothers’ surgeries were just short of 10 years old on average.
The researchers combed through the two groups’ genes to look for differences in methylation, the tiny groups of chemicals that piggyback on DNA molecules and in myriad ways, influence how that DNA is expressed. They found 5,698 genes that showed distinctly different patterns of methylation between the two groups. Those differentially methylated genes were overwhelmingly involved in insulin sensitivity and glucose regulation (processes that run amok in those with type 2 diabetes) and in inflammatory processes (a hallmark of cardiovascular diseases, auto-immune disorders and disorders of the musculo-skeletal system and gastro-intestinal tract).
The findings suggest that a woman who goes into a pregnancy extremely obese is doing more than passing on genes that predispose her child to obesity and the health effects commonly associated with it; she may also be passing on the code that inclines those genes to behave in unhealthy ways. But maternal obesity does not set that code in stone; if reversed, as it was for these women by bariatric surgery, the chemicals that direct genetic expression may well become a force for good health.