Normal weight during pregnancy is defined as a pre-pregnancy body mass index between 18.5 and 24.9 kg/m2. The emphasis here is on the pre-pregnancy body mass index, which is the pre-pregnancy weight divided by the square of the height. The normal weight gain during pregnancy is between 11.5-16kg, with an average weight gain of 0.42kg per week, at least 0.35kg per week and a maximum of 0.5kg per week, which is the ideal rate of weight gain during pregnancy. If the weight gain is too fast, it will increase the risk of huge baby, difficult shoulder delivery, postpartum hemorrhage, and also increase the chance of cesarean delivery.