In the UW study, participants were asked about the type and frequency of their physical activities, including walking, swimming, dancing, hiking and yoga; and about their diet over a three-month period, smoking history and status, and handling of stressful and emotional situations. A numerical value was given to each woman's answer, with one reflecting a healthy response and zero reflecting an unhealthy response.

Numerical values for each lifestyle behavior were added and each woman was given a total healthy lifestyle score, ranging from zero to four. When women were tested for gestational diabetes at 24 to 28 weeks pregnant, 140 women were positively diagnosed.

Data were collected as part of the Omega Study, a prospective pregnancy cohort study designed to assess dietary risk factors for pregnancy complications. Participants received prenatal care at clinics associated with Swedish Medical Center and Tacoma General Hospital from 1996 to 2008.

Results showed that each one-point increase in a woman's lifestyle score was associated with a 21 percent lower risk of gestational diabetes. Women with a lifestyle score of 0 were 4.43 times more likely to have gestational diabetes than women with a lifestyle score of 4. Women with a score of 4 were 35 percent less likely to have gestational diabetes than women with a score of 3 or less.

"Public health and clinical recommendations and interventions targeting multiple components of healthy lifestyle during pregnancy may be more effective in preventing gestational diabetes than approaches focused on a single healthy behavior," noted Badon.