 Determining your Body Mass Index (BMI) will give you some baseline information in order to figure out how much weight you should ideally gain during pregnancy.

The Imperial BMI Formula (inches and pounds)

The BMI is calculated using pounds and inches with this equation:

1.    Multiply the pre-pregnancy weight by 703

2.    Multiply your height in inches by you height in inches

3.    Divide the number from step 1 by the number in step 2

Example:

Pre-pregnancy weight = 132 lbs

Height = 67 in

1.    Multiply the weight by 703

132 x 703 = 92796

2.    Multiply your height in inches by you height in inches:

67 x 67 = 4489

3.    Divide the number from step 1 by the number in step 2:

(Current weight x 703) / (height in inches x height in inches) = BMI

92796 / 4489 = 20.67

-> My BMI is 20,67

The Metric BMI Formula (Kg and cm)

The BMI is calculated using kilograms and centimeters with this equation:

BMI = (pre-pregnancy weight / Height²)

Example:

Pre-pregnancy weight = 60 kg

Height = 170 cm

BMI = (60 / 170²) = 20.8

-> My BMI is 20,8

Here the appropriate weight gain during a singleton pregnancy

(Once again, these data and eBook only concern women carrying 1 child only – not appropriate for twin of triplet pregnancy)

Ideally, you should be at a healthy weight (BMI range of 18,6 to 24,9)and in good shape before you get pregnant. If that’s your case and if you are pregnant with 1 baby, the guideline recommends gaining 25 to 35 pounds total.

Here’s a breakdown from the Institute of Medicine of how you should gain and when:

-      First trimester: 2 – 4 pounds total

-      Second trimester: 3 – 4 pounds per month(9 to 12 lbs total)

-      Third trimester: 3- 4 pounds per month(9 to 12 lbs total)