This paper describes weight gain during pregnancy in Sweden in relation to guidelines from the United States. These guidelines take into consideration the fact that optimal weight gain during pregnancy is related to the woman's prepregnant weight in relation to her height. Almost 50 per cent of women delivering babies in Sweden during the year 2000 were obese or overweight. In the three populations studied, less than 50 per cent gained weight in accordance with the US guidelines, while more than 20 per cent gained less weight than recommended. The results indicate that, in Sweden, more attention should be paid to the body weight of women who bear children.