How do you know how much weight to gain?
Pregnancy weight gain is normal, expected, and healthy because the baby, the uterus, the placenta, the amniotic fluid need to grow. Your baby's growth and development depend on you gaining adequate weight. Pregnancy is a time to nourish yourself with healthy foods to supply enough nourishment for your baby.
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Not everyone gains exactly the same amount and how much weight gain you need depends on various factors, including your pre-pregnancy weight and body mass index (BMI). Your health and your baby's health also play a role. Being overweight or underweight during pregnancy can both have adverse effects. In the first few prenatal appointments, you should try to work with your doctor or midwife to determine what's right for you.
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What is a healthy recommended weight gain?
The Institute of Medicine (IOM) recommendations for BMI and weight gain are:
- If you were underweight before pregnancy (for the IOM, that is a BMI of less than 18.5): between about 28 to 40 pounds or 12.5 and 18 kgs extra weight during pregnancy
- If you were normal weight before pregnancy (for the IOM, that is a BMI between 18.5 and 24.9): between about 25 to 35 pounds or 11.5 and 16 kg extra weight during pregnancy
- If you were overweight before pregnancy (for the IOM, that is a BMI between 25 and 29.9): between about 15 to 25 pounds or 7 and 11.5 kg extra weight during pregnancy
- If you were obese before pregnancy (for the IOM, that is a BMI of over 29.9) about 11 to 20 pounds or between 5 and 9 kg extra weight during pregnancy
- If you are very young, then more weight gain is probably needed as teenagers may still be growing themselves.
What else besides the fetus grows?
It's not just the baby that weighs you down in those later months. Most of the weight gained in pregnancy goes into the development of tissues that allow fetal development, growth, and breastfeeding. Women must build up a variety of tissues that will support the nourishment of the fetus, and they include the fetus, the placenta, amniotic fluid, uterus, blood, and fat.
These tissues are responsible for the bulk of weight gain during pregnancy. If weight gain is too low, these tissues are not fully developed nor functional and fetal development and growth may be compromised.
Your weight alone is not a good enough indicator as to how well your baby is doing — or even of your baby’s weight gain. This depends on a lot of factors. It is not really possible to be sure of the baby’s weight before birth. Ultrasound and other tests can give an indication of how the baby is developing.