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Weight Gain in Pregnancy: What to Expect

by R. Carnavale | July 20th, 2012 | Pregnancy

When you’re pregnant, it’s normal to gain weight. Some women, like Victoria Beckham, are thin throughout their pregnancies while others really pack on the pounds (think: Jessica Simpson and Mariah Carey). The big question is, how much weight should you gain, total?

First, know that, as a pregnant woman, you have a very legitimate reason to gain weight. In fact, your baby’s health and development depend on it. Given that each pregnancy and patient is unique, always ask your health practitioner about the number of pounds he or she recommends you gain.

In general, weight gain recommendations are based on what your pre-pregnancy BMI was. BMI (body mass index) is calculated by multiplying your weight in pounds by 703, and then dividing by your height in inches squared. For instance, let’s say a woman is 5’2″ (62 inches) and weighs 130 pounds. To calculate her BMI, first multiply 130 inches by 703, which equals 72,409. Then square the height: 62 x 62 = 3844. Finally, divide 72409 by 3844 to get the BMI, which is, in this case, 19.

Here is the recommended number of pounds a woman should gain during her pregnancy:

  • Pre-pregnancy BMI is less than 18.5 (underweight): 28-40 pounds
  • Pre-pregnancy BMI is between 18.5 and 26 (normal weight): 25-35 pounds
  • Pre-pregnancy BMI is between 26 and 29 (overweight): 15-25 pounds or as advised by your health practitioner
  • Carrying twins: 35-45 pounds

Eating well is especially important during your pregnancy because you’re eating for two. Regardless of how many pounds you should add, it’s important that the gain be slow and steady and that it be within the healthy range for your body type. For a woman whose pre-pregnancy BMI is between 18.5 and 26, a typical weight gain scenario might look like this:

  • During the first trimester, when your baby is very small, plan on adding just two to four pounds for the whole trimester.
  • During the second trimester, your baby is growing a lot, so you should plan on gaining one to 1˝ pounds per week (12-14 pounds total).
  • During the final trimester, expect to gain one pound per week until delivery.

Warning: Throughout the fourth through ninth months of pregnancy, if you don’t gain any weight for at least two weeks in a row or if you find yourself gaining more than three pounds a week and it’s not due to overeating, be sure to contact your health practitioner.

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