The purpose of this study is to assess the efficacy of an electronic-based intervention to help pregnant overweight and obese women gain an appropriate amount of weight and improve their delivery i.e. to reduce the rate of labour procedures and interventions. We chose a composite outcome including instrumental delivery and Caesarean section, as clinically relevant outcomes because the mode of delivery is one of the major goals of the obstetrical management and is is strongly associated with body mass index and gestational weight gain.