Big first trimester weight gain ups diabetes risk
Women who gain weight too quickly during the first three months of pregnancy are more prone to develop pregnancy-related diabetes, new research shows.
“We found the association was stronger among women who were overweight at the start of pregnancy,” Dr. Monique M. Hedderson of Kaiser Permanente Medical Group in Oakland, California, noted in an email to Reuters Health.
This study, she added, suggests that weight gain in early pregnancy may be a modifiable risk factor for pregnancy-related, or “gestational,” diabetes.
Gestational diabetes occurs when a woman’s pancreas can no longer keep up with the body’s growing demands for the blood-sugar-regulating hormone insulin. Left untreated, high blood sugar in pregnancy can cause the fetus to grow abnormally large, increasing the risk of injury to baby and mother during delivery. While a woman’s glucose (sugar) metabolism usually returns to normal after her pregnancy is over, she runs a higher risk of developing type 2 diabetes later on.
Women typically undergo an oral glucose tolerance test between the 24th and 28th weeks of pregnancy to assess whether their body is producing enough insulin. To date, Hedderson and her colleagues note in the journal Obstetrics & Gynecology, just three small studies have looked at weight gain before this test and gestational diabetes risk.
The Institute of Medicine published guidelines on healthy weight gain in pregnancy in 2009, but stated that there is not enough evidence to say whether how much weight a woman gains influences her likelihood of developing diabetes during pregnancy.
To investigate, Hedderson and her team compared 345 women who developed gestational diabetes to 800 women who did not, all of whom delivered their babies between 1996 and 1998 and had oral glucose tolerance tests at 24 to 28 weeks’ gestation.
Women who gained weight the most slowly during their first trimester (less than a third of a kilogram per week, or just over half a pound) had the lowest risk of gestational diabetes.
Risk went up as a woman’s rate of first trimester weight gain increased; for women gaining between 0.3 and 0.4 kilograms (0.6 to 0.9 pounds), diabetes risk was about 40 percent higher; for women who gained more than 0.4 kilograms (0.9 pounds), risk increased 74 percent.
The Institute of Medicine’s weight gain recommendations are based on a woman’s body mass index (a standard measure of weight in relation to height used to gauge whether someone is overweight); for example, normal-weight women should gain between 25 and 35 pounds total during pregnancy, at the rate of about a pound a week, according to the IOM; underweight women should gain more, and overweight and obese women should gain less. Hedderson and her colleagues found that women who exceeded these recommendations were at 50 percent higher risk of gestational diabetes.
“The new IOM guidelines are the commonly accepted and used weight gain recommendations,” Hedderson said. “However, talking to women about their weight is a sensitive topic and not all OB/GYNs counsel on weight gain during pregnancy, or they wait until they see that the woman has gained too much wait before discussing it.”
She urges doctors to “talk to their patients early in their pregnancy about the appropriate weight gain, especially during the first trimester, and help women monitor their weight gain. Women should check in with their health care providers at the start of their pregnancy to plan for healthy weight gain throughout their pregnancy.”
SOURCE: Obstetrics & Gynecology, March 2010.
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