When you gain too much

Gaining too much weight during pregnancy can increase your baby's risk of health problems, such as being born significantly larger than average (fetal macrosomia), and complications at birth, such as the baby's shoulder becoming stuck after the head is delivered (shoulder dystocia). Excessive weight gain during pregnancy can also increase your risk of postpartum weight retention.

Where does pregnancy weight gain go?

Let's say your baby weighs in at 7 or 8 pounds (about 3 to 3.6 kilograms). That accounts for some of your pregnancy weight gain. What about the rest? Here's a sample breakdown:

  • Larger breasts: 1 to 3 pounds (about 0.5 to 1.4 kilogram)
  • Larger uterus: 2 pounds (about 0.9 kilogram)
  • Placenta: 1 1/2 pounds (about 0.7 kilogram)
  • Amniotic fluid: 2 pounds (about 0.9 kilogram)
  • Increased blood volume: 3 to 4 pounds (about 1.4 to 1.8 kilograms)
  • Increased fluid volume: 2 to 3 pounds (about 0.9 to 1.4 kilograms)
  • Fat stores: 6 to 8 pounds (about 2.7 to 3.6 kilograms)

Putting on the pounds

In the first trimester, most women don't need to gain much weight — which is good news if you're struggling with morning sickness.

If you start out at a healthy or normal weight, you need to gain only about 1 to 4 pounds (0.5 to 1.8 kilograms) in the first few months of pregnancy. You can do this by eating a healthy diet — no extra calories are necessary.

Steady weight gain is more important in the second and third trimesters — especially if you start out at a healthy weight or you're underweight. According to the guidelines, you'll gain about 1 pound (0.5 kilogram) a week until delivery. An extra 300 calories a day — half a sandwich and a glass of skim milk — might be enough to help you meet this goal. For overweight and obese women, the guidelines translate to a weight gain of about 1/2 pound (0.2 kilogram) a week in the second and third trimesters. Try adding a glass of low-fat milk or an ounce of cheese and a serving of fresh fruit to your diet.

Working with your health care provider

Your health care provider will keep a close eye on your weight. Do your part by eating a healthy diet and keeping your prenatal appointments. To keep your pregnancy weight gain on target, your health care provider might offer suggestions for boosting calories or scaling back as needed.

Feb. 15, 2017 See more In-depth