A change in testing could nearly triple the number of women diagnosed with diabetes during pregnancy, but would catching milder cases help mother or baby? A U.S. government panel is urging more research to find that out before doctors make the switch.

Gestational diabetes — the kind that strikes during pregnancy — is a growing problem. More women are getting it as they wait until their 30s or later to have a baby, and as they increasingly begin their pregnancies already overweight.

Kira Fonteneau was diagnosed with a mild case of gestational diabetes and quickly changed how she ate and gave birth to a healthy daughter two years ago. (Kira Fonteneau/Associated Press)

This is one of the most common complications of pregnancy, and just about every woman gets checked for it. That's because if mom's high blood sugar isn't controlled, the fetus can grow too large, leading to C-sections and early deliveries.

There are other problems, too: Mom can get dangerous high blood pressure; the baby can be born with low blood sugar; the baby's risk of obesity in childhood is increased. And while this kind of diabetes usually disappears when the baby's born, the mother is left with another risk. Months or years later, half of women who had it wind up developing full-fledged Type 2 diabetes.

Doctors today diagnose gestational diabetes in about 5 per cent to 6 per cent of U.S. pregnancies, or about 240,000 a year, according to experts convened this week by the U.S. National Institutes of Health.

Most U.S. doctors use a two-step testing method. But now there's a push for doctors to switch to a simpler one-step test that's used in other parts of the world.

The one-step approach, backed by the American Diabetes Association and World Health Organization, isn't just about the convenience of getting diagnosed in one doctor visit or two. It also would lower the blood sugar threshold for diagnosing the condition.

"The implications of this are very, very large, and there are so many unanswered questions," said Dr. Catherine Spong of the National Institute of Child Health and Human Development.

On Wednesday, the NIH-appointed panel agreed, and said many more pregnant women would be classified with gestational diabetes — 15 to 20 per cent — if doctors widely adopted the one-step approach.

Simpler testing approach

The more aggressive approach treats milder cases with diet and exercise, not medication. But that's still a lot of women who would get extra medical care, such as nutritionist visits and doctor checks of their blood sugar and their baby's growth, not to mention uncertainty about whether C-sections would increase. That could add up to hundreds of millions of dollars in health costs annually.

But there's been no study of whether treating cases milder than are diagnosed today makes any difference to the health of mother and baby, the experts concluded.

"If we can extend benefits to mothers, their unborn children … and impact their future health care, everybody would want to get on board even if it were more expensive," said Dr. Peter VanDorsten of the Medical University of South Carolina. He chaired the NIH panel. Doctors aren't required to follow its advice.

He called for quick research to settle the debate, saying, "We absolutely left the door ajar for reconsideration."

What's the test? Under the two-step method, nearly every woman drinks a super-sweet liquid, and has a blood test an hour later to see how the body processes the sugar. Those who fail repeat the test with a larger drink and three hours of blood tests. With the one-step method, everyone would get a single two-hour test.

The push to switch came after a study of 25,000 pregnant women in nine countries. It found that various health risks for mother and child gradually grew as mom's blood sugar rose above normal levels, even if she wasn't officially diabetic.

Some doctors already are trying the simpler approach. The Oregon Health & Science University began using it last summer, and gestational diabetes cases doubled, obstetrics chairman Dr. Aaron Caughey told the NIH meeting. But his medical center decided it's worth trying because even women with mild diabetes could benefit from nutritional counseling that insurance doesn't always cover unless they're diagnosed, Caughey said.

Wednesday's report urged doctors also to consider the anxiety that a diagnosis of even mild gestational diabetes can bring.

In Birmingham, Ala., attorney Kira Fonteneau was diagnosed with gestational diabetes after traditional two-step testing. She cried at the news even though doctors made clear she had a very mild case. She wasn't overweight, but diabetes runs in the family.

Armed with a nutritionist's advice and regular blood-sugar checks, Fonteneau quickly changed how she ate, cutting back on carbohydates. She got better.

"Knowledge is power," she said. "You want to have a healthy baby."

Her daughter Sydney, now 2, was born a healthy 5 pounds, 11 ounces. Fonteneau said she bounced back faster, gaining far less during her pregnancy than is typical for her family. She said she will pay more attention to her own health knowing she's at increased risk for Type 2 diabetes later on.