Purpose: Obesity is a problem that affects almost one third of all preg nant wo men. To establish a data base for further studies we looked at the evolution of weight and body mass index before, during and one year after pregnancy. Material and Methods: Out of 2220 women who gave birth at the Womens University Hospit al Tübingen in 2001, 1000 were selected for further evaluation in accordance wi th our inclusion and exclusion criteria. Data regarding pregnancy and delivery w ere collected retrospectively. One year after delivery, the women were contacted by phone and interviewed regarding their weight development. Results: Out of 10 00 women, 713 women were successfully contacted. Average age was 31.7 years. Ave rage weight before pregnancy was 65.9 kg, average weight-gain during pregnancy was 13.2 kg. Average weight one year postpartum was 66.5 kg. Before pregnancy, 2 3.3%of all women were overweight or obese. One year after delivery, 27.0%fell into these two categories (p<0.01). Only about one third of all pregnant women g ained weight within the recommended limits. Conclusion: Almost one third of wome n are overweight or obese before and one year after pregnancy and delivery. Weig ht changes during and after pregnancy varied widely. Overweight status before pregnancy and -for normal-weight wom en -weight gain in excess of the recommended maximal 16 kg during pregnancy wer e important risk factors for weight retention one year after delivery. The proba bility of a normal-weight woman to be overweight or obese one year after pregna ncy is 10%. Purpose: Obesity is a problem that affects almost one third of all preg nant wo men. To establish a data base for further studies we looked at the evolution of weight and body mass index before, during and one year after pregnancy. Out of 2220 women who gave birth at the Women’s University Hospit al Tübingen in 2001, 1000 were selected for further evaluation in accordance with the criteria of our inclusion and exclusion criteria. Data regarding pregnancy and delivery w ere collected retrospectively. One year after delivery, the women were contacted by phone and interviewed regarding their weight development. Results: Out of 10 00 women, 713 women were successfully contacted. Average age was 31.7 years. Ave rage weight before pregnancy was 65.9 kg, average weight-gain during pregnancy was 13.2 kg. Average weight one year postpartum was 66.5 kg. Before pregnancy, 2 3.3% of all women were overweight or obese. One year after delivery, 27.0% fell into these two categories (p <0.01). Only about one third of all pregnant women g ained weight within the recommended limits. Conclusion: Almost one third of wome n are overweight or obese before and one year after pregnancy and delivery. Weig ht changes during and after pregnancy more widely. Overweight status before pregnancy and -for normal-weight wom en -weight gain in excess of the recommended maximal 16 kg during pregnancy wer e important risk factors for weight retention one year after delivery. The proba bility of a normal-weight woman to be overweight or obese one year after pregna ncy is 10%.