Image: JoNel Aleccia
By JoNel Aleccia Health writer
updated 5/23/2011 9:15:22 AM ET 2011-05-23T13:15:22

A British doctor is hoping to battle obesity in babies still in the womb by giving their heavy mothers pills to prevent more weight gain.

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Dr. Hassan Shehata wants to keep potentially pudgy babies from tipping the scales too high at birth, which can expose them — and their moms — to serious complications and lifelong problems.

The solution, he believes, is to give the pregnant, obese women the popular diabetes drug metformin — even though the expectant mothers don’t actually have the disease.

“Metformin is now a drug which is very safely used in pregnancy for gestational diabetes,” said Shehata, a maternal health specialist at Epsom and St. Helier University Hospitals NHS Trust in Surrey, England. “We now wish to examine its potential for obese women who do not have diabetes.”

About 75 women have enrolled so far in the clinical trial that eventually will expand to eight sites and 2,178 women, according to registration documents at

The trial, which began last fall and is expected to last until December 2013, will compare the results of participants who take up to 3,000 milligrams of metformin daily with those who take placebos. Both groups will follow diet and exercise plans.

Fewer obese babies
Shehata hopes to show that fewer babies born to women who take the drug will have high birth weights — 10 pounds or more — which lands them in the 90th percentile for weight and effectively brands them as obese. Smaller babies will result in fewer complications for mother and child, he says.

“By dropping the baby’s weight, the prevalence of high blood pressure, gestational diabetes and hemorrhage will be lower,” Shehata said, listing several common causes of maternal complications and death. “For me, I have to say, metformin ticks all the boxes.”

The trial also will track how much weight the mothers gain, and complications of pregnancy including development of gestational diabetes, high blood pressure, C-sections, birth trauma and other problems.

Other experts, however, say the research raises questions about giving women diabetes drugs rather than relying on diet and exercise alone to combat obesity, especially during pregnancy.

Some researchers have experimented with using the drug in non-pregnant, obese women, "but it is not an intervention of choice," said Dr. Raul Artal, professor and chair of the obstetrics, gynecology and women’s health department at the St. Louis University School of Medicine.

“I can tell you that in my own clinic, where I see a lot of pregnant, obese women, we prescribe a diet where they maintain their weight and on occasion also lose weight,” Artal said.

Shehata counters that lifestyle changes alone might not be realistic for women who are already obese and struggling with weight gain when they become pregnant.

“Diet and exercise has not worked, several trials have shown,” Shehata said.

Taking metformin may help, he said. The drug works by increasing the body’s sensitivity to insulin, reducing insulin resistance, a common problem in late pregnancy — and in already obese women, Shehata said.

Women who are obese put on more weight during pregnancy than normal-weight women — and not because they're "pigging out and eating all that food," Shehata said.

"Their bodies are so insulin-resistant that everything they eat becomes fat," he explained.

Metformin taken during pregnancy appears to be safe for mothers and babies, judging by studies of the drug’s use to control gestational diabetes, Shehata said.

Tackling the growing problem of obesity during pregnancy is crucial, experts say. In the U.S., about 24 percent of women of childbearing age, 18 to 44, were obese in 2009, up from 15 percent in 1999, according to figures from the March of Dimes.

“This has become a big thing. Obesity is something that is not a friend of pregnancy,” said Dr. Luis B. Curet, a professor emeritus of obstetrics and gynecology at the University of New Mexico.

Should obese women gain during pregnancy?
How much weight obese women should gain during pregnancy is a controversial topic. Guidelines from the U.S. Institute of Medicine suggest that women with body mass indexes of 30 or more could gain about 15 pounds during pregnancy. That compares to a recommended gain of 25 pounds to 35 pounds in normal-weight women with a BMI of between 19.8 and 26 and 15 pounds to 25 pounds for women who are overweight, with a BMI between 26.1 and 29.

But experts such as Artal, the St. Louis specialist, long have argued that the IOM recommendations are outdated and that obese women actually should strive to gain little or no weight — or even lose a few pounds — in order to preserve their health and the health of their babies.

Whether metformin is actually the answer remains to be seen. There are questions about the long-term effect on the fetus, especially the fetal liver, Artal said. And researchers need to make sure that weight of the baby goes down because of metformin’s insulin effect, not some other reason, Curet noted.

Shehata is confident that those questions will be resolved. His study passed muster with ethics committees at the National Health Service. Now, he’s just waiting for the first babies to be born.

“I’m very confident about it and I don’t think there are any issues,” he said.

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