Gaining too much weight during a pregnancy will make you susceptible to pregnancy induced hypertension. However, recent trends have been seeing mothers-to-be that are too slim. It is said that not gaining enough weight will result in not only a smaller infant but also makes you susceptible to lifestyle related diseases. In any case, weight control during gestation is very important. 

The weight a pregnant woman gains until birth mostly consists of the weight of the infant (fetus), placenta, amniotic fluid and blood. A newborn's average weight is approximately 3 kilograms. It is said that a mother-to-be's body stores up necessary nutrients for birth and breastfeeding during pregnancy as well. In recent time, weight gain calculated according to each individual's pre-pregnancy weight seems to be the most ideal.