NEW YORK – Treating even mild diabetes that develops during pregnancy helps keep moms and babies from gaining too much weight and makes for easier deliveries, new research shows.

Pregnant women in the U.S. are routinely tested and treated for high blood sugar levels, although it hasn’t been clear whether treating the mildest cases really benefited them and their infants.

In a study of 950 women, those with mild gestational diabetes who were treated had fewer overly large babies, fewer cesarean sections and fewer pregnancy complications, compared to women who didn’t have their diabetes treated.

“There is every reason to fully treat women with even the mildest (gestational diabetes) based on our results,” said the study’s leader, Dr. Mark Landon of Ohio State University Medical Center in Columbus.

Gestational diabetes begins during pregnancy and usually goes away after childbirth. It affects as many as one in seven pregnant women, depending on the population. The mother’s elevated blood sugar can cause the fetus to grow too large, sometimes requiring a C-section and can bring on other health problems for the mother and baby.

Risk factors include being over 25, being obese and a family history of diabetes.

Medical groups support testing pregnant women for the condition and treatment, although the U.S. Preventive Services Task Force, a government health panel, said last year there wasn’t enough evidence to recommend screening.

Landon said he’d had doubts about treating mild cases, and was surprised by the study’s results.

“I did it, yet I wondered, ‘Was I overtreating?”‘ he said.

For the government-funded study, 958 women with mild gestational diabetes were recruited at 15 medical centres. They got either diabetes treatment or standard prenatal care. Treatment included diet counselling and insulin if needed to get their blood sugar under control.

In the treatment group, there were fewer babies of unusually large size (seven per cent versus 15 per cent in the untreated group) and fewer babies weighed more than about nine pounds (six per cent versus 14 per cent). On average, the treated women gained five fewer pounds after their diagnosis than the untreated ones.

There were also fewer C-sections and cases of preeclampsia, a serious pregnancy complication. There were no deaths in either group, and no difference in other birth-related complications.

Landon noted that a “remarkable” 93 per cent of the women in the treatment group kept their blood sugar under control with diet alone; only seven per cent needed insulin.

The findings are reported in Thursday’s New England Journal of Medicine.

Dr. David A. Sacks of Kaiser Foundation Hospital in Bellflower, Calif., said switching to a healthier diet could help other pregnant women limit weight gain, too. More large babies are born to overweight or obese women who don’t have diabetes, he said.

“This is a real easy therapy to apply to every single pregnant lady,” said Sacks, who wrote an editorial about the study in the journal.

Even before she got pregnant, Lorenda Donaugh knew all about gestational diabetes. She works with Landon at Ohio State, doing ultrasounds for his patients, and ended up becoming one after she was diagnosed at 28 weeks with a mild case.

“I knew it was going to be hard work. It takes a lot of time and planning,” said the 27-year-old, who lives in the Columbus suburb of Westerville.

Donaugh, who was not part of the study, monitored her blood sugar several times a day, modified her diet and took extra walks. She eventually took a diabetes medication.

Planning meals and cutting back on sugar was the hardest part, she said. Whenever she was tempted, she thought of her baby. “Being pregnant, you have all those cravings, but you still have to limit that food,” she said.

The work paid off. She delivered a healthy daughter on Sept. 14. Adelynn weighed six pounds, four ounces and her mom had only gained a modest 22 pounds.