Maternal obesity raises disease, defect risks in offspring

It has long been known that obesity impairs our metabolism and predisposes to diabetes and heart disease — now research published in The Journal of Physiology has shown that the effects of maternal obesity pass across generations to offspring, accelerating the rate of ageing of metabolic problems that occur in normal life.

Researchers at the National Institute of Medical Sciences and Nutrition Salvador Zubiran (INCMNSZ) led a recent study into the offspring of obese rat mothers, observing the offspring throughout their lives to determine the rate at which they aged. Offspring of obese mothers had more body fat and showed early pre-diabetic signs such as an early rise in insulin resistance, increasing susceptibility to diabetes.

Offspring of the obese mothers also showed impaired function of their mitochondria, the power stations of cells that generate the energy cells need to function properly. These changes make it more likely that organisms will develop heart disease.

Interestingly, some of the unwanted outcomes resulting from maternal obesity were different in male and female offspring. The reason for this is not clear, but it is thought to be hormonal in nature.

These new findings add to the accumulating evidence for the influence of conditions in the womb and early life on the physiology of the offspring, which thus impacts their susceptibility for diseases and the rate at which they age.

“This reinforces the link between maternal obesity and the ageing of offspring, specifically around the increased likelihood of developing diabetes and heart disease,” said senior author Elena Zambrano, from INCMNSZ. “Encouragingly, in previous studies we have shown that exercise by the offspring can help offset the risks brought about by maternal obesity.”

Obese women looking to fall pregnant may also wish to consider gastric bypass surgery before conception, with a separate study from Swedish researchers and published in JAMA finding that the resulting weight loss and improved blood sugar control could reduce the risk of major birth defects.

Obesity and poor blood sugar control have in previous studies been linked to an increased risk of health complications for both mothers and their infants. However, there have been concerns dating back to the 1980s that bariatric surgery could increase the risk of major birth defects, with studies showing that weight-loss surgery may increase the risk of various nutrient deficiencies, including iron and folate.

Researchers from Karolinska Institutet and Örebro University thus set out to examine data on more than 33,000 births in Sweden between 2007 and 2014. Of these, 2921 were children born to mothers who underwent a gastric bypass and 30,753 were children born to women who weighed about the same as the gastric bypass women did before their surgeries. The women in the surgery group lost an average of 40 kg and weighed around 82 kg at their first prenatal check-up. Their use of diabetes medication decreased to 1.5% from 9.7%.

The study showed that the risk of major birth defects was about 30% lower in children of mothers who had gastric bypass surgery than in children of severely obese mothers. The risk of major defects was 3.4% in children born to women who had had gastric bypass surgery, which is in line with the risk of major defects in children born to normal weight women (3.5%). For women who at their first prenatal check-up had a body-mass index comparable to that of the gastric bypass patients’ pre-surgery weight, the risk of major birth defects was 4.9%.

“This study shows that weight loss and improved blood sugar control in the mother can actually result in a lower risk of birth defects in the child,” said study co-author Professor Martin Neovius, from the Karolinska Institutet. “It should help reduce fears that bariatric surgery increases the risk of birth defects in the event of future pregnancy, assuming that surgery patients take their recommended nutritional supplements.”

Study co-author Olof Stephansson, also from the Karolinska Institutet, added that it is important that surgery patients “receive special antenatal care, including additional ultrasounds to monitor foetal growth and detailed nutritional counselling that include administration of supplements necessary after weight-loss surgery. Antenatal care providers should also check for nutrition deficiencies in addition to iron, such as folic acid, calcium and vitamin B12.”

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