Losing weight before a pregnancy can avert possible negative health consequences for a mother’s child. Six out of every 10 women in the U.S. are obese, which can severely impact their reproductive health. Infertility, abnormal menstrual cycle, and pregnancy complications like gestational diabetes are all more common in women who are overweight.

Maternal obesity also increases the likelihood that a child will suffer from the same condition and elevates the risk of diabetes and hypertension later in life. However, these disorders, for both mother and child, can be reversed by sustained weight loss in the parent.

Weight loss surgery offers a quick route for accomplishing this, but new evidence in the journal Science Translational Medicine suggests that some procedures may be more detrimental for future offspring than others.

"Maternal obesity and diabetes have long-term negative health consequences for offspring in both rodents and humans," said lead author Dr. Bernadette Grayson of the University of Cincinnati. "Bariatric surgical procedures like vertical sleeve gastrectomy are still the most effective way to achieve sustained weight loss and improvements in glucose levels."

However, Grayson’s investigation found that vertical sleeve gastrectomy (VSG), a procedure where the stomach is reduced to the size and shape of a banana, still yields long-term consequences for offspring.

How Vertical Sleeve Gastrectomy Works

Overweight female rats given the appetite-reducing surgery experienced all of the personal benefits of the procedure — weight loss, lower cholesterol, improved glucose control — but the birth weights of their future offspring were significantly lower.

In addition, these ‘rat kids’ had a tendency to gain more weight once they reached puberty, compared to offspring from mothers who didn’t have VSG.

“Offspring of VSG rats showed a greater propensity to gain body fat and develop glucose when they were given access to a high-fat diet following puberty,” said senior author Dr. Randy Seeley, director of the Cincinnati Diabetes and Obesity Center.

The authors attributed these detrimental outcomes to the fact that VSG elminates the part of the stomach that produces the appetite-inducing hormone ghrelin. Prior work in rodents has shown that artificially reducing ghrelin causes lower birth weights.

The authors point out that other operations, like gastric banding and Roux-en-Y gastric bypass, have not been associated with poor outcomes in human infants in multiple studies, while still providing weight loss benefits.

"In the case of VSG, the hormonal changes induced by the surgery, which aid in weight loss, may be the very same culprits for the reduced growth. This is something we will be looking at in future research," continued Seeley. "It may not be sufficient enough just to get mom healthier before she conceives; how she gets healthier seems to matter."

He and Grayson plan to explore why certain types of weight loss remedies and surgeries have a grander impact on reproductive and prenatal health. In addition, future work needs to confirm whether the same rules that apply to rats are also in play with humans.

"The interaction between diet and the maternal environments—the uterus and placenta, for example—may impact susceptibility to metabolic disease in offspring," concluded Seeley.

Source: Grayson BE, Schneider KM, Woods SC, Seeley RJ. Improved Rodent Maternal Metabolism But Reduced Intrauterine Growth After Vertical Sleeve Gastrectomy. Science Translational Medicine. 2013.