Understanding How Obesity Could Be Passed From Mother to Child

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elvira-isganaitis-md-labphotoforprIt’s well known that babies born to women who are obese have a higher risk of developing obesity later in life. It hasn’t always been clear why, but researchers at Joslin Diabetes Center have recently uncovered a few factors that could play a role. In a study recently published in the International Journal of Obesity, researchers clarified some of the process through which obesity risk is passed from a mother to her baby.

The researchers analyzed cells from the vein within infants’ umbilical cords, and they saw that some of the genes responsible for helping metabolize lipids, and for generating energy in the mitochondria, don’t turn on properly in babies born to obese mothers.  This suggests that the baby’s metabolism may be altered from day one, which could interfere with the ability to deal with nutrient overload, and might make the babies more prone to turning nutrients into stored fat, which can lead to obesity and other metabolic problems later in life.

To understand more about why these metabolism genes weren’t turning on (or expressed) correctly, they analyzed the nutrients and hormonal signals in cord blood. They saw increased levels of insulin, free fatty acids and saturated fatty acids, which is similar to patterns seen in obese or pre-diabetic individuals. (Genes turning on or off is also known as ‘gene expression,’ the phrase more commonly used in the lab).

“By analyzing the composition of the infants’ cord blood, we tried to gain insight into what factors might be triggering the differences in gene expression we observed.  We found increased levels of insulin in cord blood from infants of obese women,” said Elvira Isganaitis, M.D., M.P.H., Assistant Investigator and Staff Pediatric Endocrinologist at Joslin Diabetes Center and Instructor in Pediatrics at Harvard Medical School. “Insulin does not cross the placenta, so it is definitely coming from the infant (not maternal transfer), and may suggest that infants were being exposed to higher glucose levels in utero, which stimulated their insulin production.”

Fatty acids, on the other hand, can cross the placenta which means those problematic molecules could either be coming from the mother or from the baby. Their increased abundance could be caused by mothers’ diet, how nutrients are delivered to the placenta, or how the mothers’ or babies’ bodies handle different fats.

One way or the other, says Dr. Isganaitis, “they do show that the infant cells may be experiencing nutrient overload, and that excess lipids could be driving the differences in gene expression.”

There is good news from this study. Understanding the precise mechanisms by which maternal obesity contributes to childhood obesity may allow researchers in the future to predict which infants are at higher risk, and provide them with individualized nutrition counseling, or other ways of preventing childhood obesity.  Even better, improving the health of the overweight mother through exercise or possibly through nutritional supplements, would have the potential to improve both a mother’s health during pregnancy, but would also improve the health of the baby in the long term.   “From a public health perspective, pregnancy is a really exciting time during which women are engaging frequently with their health care providers, and are highly motivated to do whatever they can to improve the health of their baby.  There is a potential to improve the health not only of mothers, but also the health of the next generation, through the care that we provide to pregnant women.”


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