The objectives of this population based cohort study of 3997 women was to determine the incidence of falling and risk factors related to falls during pregnancy. Birth certificate data identified women who had delivered a child within the previous 2 months. Subjects were reached either by phone, internet or mailed surveys. The women were asked about health issues and activities at the time of the fall. Of the 3997 participants, 1070 reported falling at least once (27%) during their pregnancy. Of those 1070 35% fell two or more times, 20% sought medical care and 21% had two or more days of restricted activity. Women aged 20-24 years had an almost two fold risk of falling more than those over 35 years (odds ratio 1.9; 95% confidence interval 1.4, 2.7). Characteristics of falls included: indoors (56%), on stairs (39%) and falling from a height greater than three feet (9%) (not mutually exclusive). Though 27% of women fell while pregnant, 10% experienced two or more falls. Pregnant women should be aware of the risk factors of and situations related to falls. There is an urgent need for primary prevention in this high risk group.