Randomized Controlled Trial

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POSITIVE: See Quality Criteria Checklist below.

The aim of the study was to evaluate if a lifestyle intervention since early pregnancy is feasible in improving the glucose tolerance of women at a high-risk for GDM in Finland.

Pregnant women at eight to 12 weeks gestation were given a two-hour OGTT: They were included if they had one or more the following risk factors for GDM:

• BMI over 25kg/m², previous history of GDM or birth of child over 4.5kg; aged over 40 years, family history of diabetes (parents, children, siblings or grandparents)
• The venous plasma glucose concentration after 12 hours' fasting in the morning was 4.8mmol to 5.5mmol per L and two-hour OGTT plasma glucose over 7.8mmol per L.

Pregnant women at eight to 12 weeks gestation with no history of GDM or venous plasma glucose after 12 hours fasting in the morning under 4.8mmol or over 5.5mmol per L and two-hour OGTT plasma glucose over 7.8mmol per L.

• Recruitment: Women were recruited from two rural municipalities (Kahua-joki and Lapua, Finland) who attended maternal health care units during gestational Weeks Eight through 12
• Design: High-risk women were randomized to lifestyle intervention or close-follow up group by the study physician using a computerized randomization list
• Blinding used: Health care nurses who scheduled the study visits did not have access to the randomization list. Obsetricians who were not study physicans made decisions concerning the beginning of insulin treatment.

 

Statistical Analysis

Statistical analyses were based on the intention to treat Differences between the groups were analysed by Student’s T-test for continuous variables and the chi-square test and Fisher’s exact test for categorical variables. Statistical significance was set at the 95% level (P<0.05).

Close Follow-Up Group

The women were informed of the results of the OGTT during gestational weeks eight through 12 All women were also given general information on diet and physical activity to decrease the risk of GDM during pregnancy Dietary information was collected three times during pregnancy. They returned a self-reported exercise history and a monthly questionnaire of physical activity. The women were followed-up in the prenatal clinic of the municipal health center at one-month intervals, according to standard care in Finland.

Intervention

Lifestyle Intervention Group

Dietary goals 

• Energy recommendations: 30kcal for normal weight and 25kcal per kg of body weight per day for overweight women
• Carbohydrate: 50-55% of energy
• Fiber: 15g per 1,000kcal
• Fat: 30% of energy; saturated fat, less than 10% of energy
• Protein: 15-20% of energy
• Women were encouraged to eat a diet rich in vegetables, berries and fruits, and to use low-fat dairy products, low-fat meat, soft margarines and vegetable oils, and whole grain products
• The nutritionist gave dietary advice tailored to each subject individually six times. The three-factor eating questionnaire was used in the beginning of pregnancy and at weeks 36 through 40. 
• The nurse in the health care centers had on average 13 appointments with the intervention women. The intervention women had no instruction on self glucose monitoring before GDM was diagnosed.

Physical activity

• Moderate-intensity physical exercise during pregnancy was recommended. The formula (220 - age) × 0.65-0.75 was used to estimate the heart rate goals for moderate intensity exercise. Other measures of exercise intensity included the “talk test" i.e., exercise at an intensity in which the woman is able to maintain a conversation during exercise. A target rating of 12 to 14 on Borg’s scale of perceived exertion was also used. The pregnant women had six appointments with the physiotherapist. During sessions, the physiotherapist motivated the women individually to continue exercising during pregnancy or to start exercising and also gave written instructions for exercise and self care.
• Previously sedentary women were instructed to begin with 15 minutes of continuous exercise three times per week, increasing gradually to 30-minute sessions four times per week. The goal of the exercise intervention was 30 minutes of daily physical activity if the woman previously exercised less than 2.5 hours per week and 45 minutes of activity if the woman already engaged in 2.5 hours or more per week of physical activity.
• Recommendable types of exercise were brisk walking, Nordic walking, swimming, cycling and cross-country skiing. If the BMI of a woman was over 30kg/m² and the woman was not physically active before pregnancy, the exercise was started with 15 minutes per day three times per week. Women were offered both aerobics classes and aquafit classes weekly.

Timing of Measurements

• Two-hour OGTT was repeated during gestational weeks 26 to 28
• Four-day food records were collected at baseline, weeks 26 to 28 and at the end of pregnancy
• Three-factor eating questionnaire was completed twice
• Monthly exercise reporting diaries were collected six times.

Dependent Variables

• Diagnosis of GDM (according to the World Health Organization), fasting plasma glucose 5.6mmol per L or two hours plasma glucose 7.8mmol per L
• Maternal outcomes (weight gain during pregnancy, pre-eclampsia, induction of labor, lacerations, Cesarean deliveries)
• Neonatal outcomes (mean birth weight, macrosomia, gestational age, admissions to the neonatal intensive care unit, jaundice requiring phototherapy or respiratory distress).

Independent Variables

Lifestyle intervention (dietary counseling and physical acitivity).

Control Variables

Weeks of gestation at baseline.

• Initial N: 60
• Attrition (final N): 54 (27 in Lifestyle Group, 27 in Close Follow-Up Group)
• Age: 29.1 years in Lifestyle Group, 29.8 years in Close Follow-Up Group
• Ethnicity: N/A.

Other Relevant Demographics

• Anthropometrics 
  • BMI
    • Lifestyle group: 27.3±6.0
    • Close Follow-Up Group: 25.5±3.4 (NS).
  • BMI over 25kg/m²
    • Lifestyle Group: 18 (60%)
    • Close Follow-Up Group: 17 (56.7%; NS).
• Location: Finland.

• There were no significant differences between groups in total weight gain, weight gain at the end of pregnancy, fasting glucose, OGTT one-hour glucose, two-hour glucose or the area under the curve. Neither group had any individuals who required insulin therapy.
• Gestational diabetes incidence was three (11.1%) in the Lifestyle Intervention Group and one (3.7%) in the Close Follow-Up Group (NS)
• The Intervention Group had a lower weight gain during pregnancy: 11.4±6.0kg vs. 13.9±5.1kg (P=0.062), adjusted by the prepregnancy weight
• The mean birth weight was greater, 3,871±567g in the Lifestyle Intervention Group (P=0.047, adjusted by the prepregnancy weight of the women), compared with the Close Follow-Up Group: 3,491±573g.

• Early intervention with an OGTT and simple lifestyle advice is feasible
• A more intensive lifestyle intervention did not offer additional benefits with respect to glucose tolerance, although it tended to ameliorate the weight gain.

University/Hospital:

Seinajoki central hospital, Kuopio University Hospital, University of Eastern Finland