Calculating Weight Gain during Pregnancy

Adequate range weight gain during pregnancy is determined according to the pre-pregnant Body mass index (BMI).

1. Calculate Body mass index (BMI)


2. Establish a weight gain range goal

Try to achieve at least the lower limit of the weight gain specified by the BMI.

If its least than the least limit range; weight gain is insufficient.
If weight gain is between ranges; weight gain is adequate.
If its higher than the high limit; weight gain is excessive.

During pregnancy weight gain should be at least 10 lb. (4.54 kg.) by 20 weeks and about 1 lb. (0.45 kg.) a week thereafter.

If a woman is underweight she may gain more and if she is overweight she may gain less.

3. Review diet

Every woman should eat what she thinks its working for her. But she must try to eat quality food and well balanced diet and supplements should be supplemental not substitutes of food.


Rosa is an 21-year-old G1P0 at 39 weeks gestation. She is 5’2″ tall, she weights 155 lb. (70 kg.) Her pre-pregnancy weight was 128 lb. In what category is her total pregnancy weight gain?

1. Calculate pre-pregnancy Body Mass Index (BMI)
Body Mass Index (BMI) = 23.41

2. Subtract her pre-pregnancy weight from actual weight.
145 – 128 = 27

3. Locate weight ranges according to her pre-pregnancy BMI
According to her pre-pregnancy BMI she should gain between 25 – 35 lb. she has gain 27 lb. which is an adequate weight gain.

If a mother seems to be gaining weight more rapidly than usual

  • Check for a fetal growth spurt.
  • Double-check the diet

Risks for underweight woman who gains very slowly

  • Anemia
  • Preeclampsia
  • Premature labor
  • Prolonged labor
  • Postpartum hemorrhage
  • Poor recovery
  • Postpartum depression

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