Is a novel approach of lifestyle intervention program in pregnancy reasonable for primary prevention of obesity, is it feasible in practice and efficient?1. Systematic literature research in the database PubMed showed that energy restriction has a significant effect on weight gain in obese pregnant women. Moderate physical activity during pregnancy increases the fitness and is not harmful. Effects on maternal weight gain are given with significant reductions of 0,6 - 0,9 kg, obese pregnant women benefit most. Lifestyle interventions are too heterogeneous to pool together in order to calculate an effect estimator for the primary prevention of exsessive gestational weight gain.2. In the region of East Westphalia-Lippe, there is only a small range of exercise classes for pregnant women, which reached 7,5 to a maximum of 20 % of the target group, consisting mainly of yoga and water aerobics.3. The concept of a preventive lifestyle intervention program during pregnancy is feasible and established. The validity of data is low. Gestational weight gain of the participants is located as well as the control group more than 50 % outside the recommendations. Program participants exercise significantly longer over the course of pregnancy, more frequent and more intense than the control group. Particpants benefit in terms of avoidance of orthopedic problems (back pain, joint pain, p < 0,05) and earlier recovery of physical performance after delivery (p < 0,01). Lifestyle interventions consisting a diet and exercise program in pregnancy are necessary, practically feasible and reasonable as a part of an overall concept for the prevention of obesity. The benefit of the program „Active and healthy through pregnancy“ is mainly reduction of back pain and joint pain and the maintainance of fitness and physical performance during and after pregnancy.