The objectives of this prospective study were to compare physical activity in 70 normal-weight women with a body mass index (BMI) 20-25 kg/m(2), and 70 obese with a BMI ≥ 30 kg/m(2), before and during pregnancy, and to compare compliance using the pedometer. Physical activity before pregnancy was assessed by questionnaires and during pregnancy by a pedometer worn on 7 consecutive days every 4th week. Obese women were less physically active than normal-weight women both before (p