Using this calculator, both the woman and the obstetrician-gynecologist can keep track of the weight that should be at each stage of pregnancy, which means the normal development of the fetus. There is a weekly weight gain chart. The attending physician provides a BMI (body mass index) table to observe the development of the fetus. It is worth noting that only up to 30% of the gained weight is the fetus, the rest is amniotic fluid (about 10% or up to 2 kg), breast enlargement up to 1 kg, body fat up to 3 kg and an increase of BV (blood volume) up to 2 kg.
In order to precisely calculate the rate BMI is used. It's a measure of the weight compared to the height, which is found using the formula:BMI = weight (kg) / height (m2)
If the BMI is up to 18.5, this indicates underweight, up to 25 is within normal parameters, up to 30 is overweight, over 30 is obesity of various degrees. After that, using the table, the indicators are compared. For example, at 20 weeks of pregnancy with a BMI below 25, the weight gain should be about 4.8 kg. However, using a calculator the weight before pregnancy, current weight, and height are recorded.