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NEW YORK (Reuters Health) - Pregnant women with a history of pregnancy-related diabetes, also called gestational diabetes, have a good chance of developing the condition again, suggests a large new study. Researchers found that the risk of having gestational diabetes during a future pregnancy increases with each previously affected one -- from 41 percent after the first to 57 percent after two pregnancies complicated by gestational diabetes. Gestational diabetes typically strikes during late pregnancy and is characterized by high blood sugar that results from the body's impaired use of insulin. While it rarely causes birth defects, complications can arise that threaten the health of both mom and baby. "Because of the silent nature of gestational diabetes, it is important to identify early those who are at risk and watch them closely during their prenatal care," lead researcher Dr. Darios Getahun of Kaiser Permanente Southern California Medical Group, in Pasadena, told Reuters Health in an email.In an attempt to distinguish factors that put women at risk, Getahun and his colleagues studied the first two pregnancies of about 65,000 women and the first three pregnancies of about 13,000 women who sought care at their health center between 1991 and 2008. Approximately 4 percent of the women developed gestational diabetes during their first pregnancy, they report in the American Journal of Obstetrics and Gynecology. This matches the U.S. rate estimated by the American Diabetes Association.The team found that these women were about 13 times more likely to develop it again in their second pregnancy, compared to women without previous gestational diabetes. Among third pregnancies, the risk of diabetes for women who had two previous cases rose to 26 times that of women without any history of gestational diabetes. Looking more closely at the data, it appeared that the most recent case of gestational diabetes was the most influential: About 44 percent of women with a diagnosis in their second but not first pregnancy developed gestational diabetes, compared to 23 percent of those with the condition in their first but not second pregnancy. Hispanics, Asians and Pacific Islanders had approximately double the risk of gestational diabetes compared with white women, after taking into account factors such as age and education. The researchers guess that the relatively high consumption of rice in the latter two groups may cause elevated sugar and insulin levels, potentially triggering the condition. The study, which was supported by funds from Kaiser Permanente, did not take into account lifestyle factors such as weight. This, the researchers say, limits the findings' applicability given that overweight and obesity -- now affecting approximately one out of every three women of childbearing age -- is thought to contribute to the recurrence of gestational diabetes. The American College of Obstetrics and Gynecology and the American Diabetes Association both recommend that women at risk of type 2 diabetes be counseled on the benefits of modifying their diet, exercising and weight loss. This group includes those with a history of gestational diabetes. "Early identification of at-risk populations and the timely initiation of a (post-delivery) lifestyle intervention may help to prevent gestational diabetes and related adverse pregnancy outcomes," Getahun told Reuters Health. American Journal of Obstetrics and Gynecology, online July 14, 2010.