Pregnancy Weight Gain

Guidelines to healthy weight gain in pregnancy

During pregnancy, weight fluctuations are expected. Not only are you literally carrying another person around everywhere you go, but you also have to eat more to nourish your growing baby with the nutrients it needs for good health. The exact amount of pregnancy weight gain you should expect varies, and it depends on your body type and how much you weighed before you became pregnant. However, while no two women are exactly alike and weight gain during pregnancy varies from woman to woman, there are established patterns that most pregnancies follow.

Weight Gain in Pregnancy: What to Expect

Your pre-pregnancy body mass index (BMI) rating is typically a good indicator of how much weight you should expect to gain during pregnancy. If you had a healthy BMI, falling between 18.5 and 24.9, it is typical to see between 25 and 35 pounds of weight gain if you follow a healthy diet for pregnancy. Women who were underweight, with BMI scores of 18.4 and below, will usually see more dramatic weight gains of up to 40 pounds. Women with BMIs above 25 will usually gain only 10 to 20 pounds during pregnancy.

Since a typical baby weighs around 7 or 8 pounds, where does all that other weight come from? The placenta, amniotic fluid and the growing muscles of your uterus account for 5 or 6 pounds. Your own blood volume and other bodily fluids increase by another 8 pounds. In preparation for breastfeeding, your breasts will gain an extra 2 pounds and your body will store up to 7 pounds of fat to use for milk production later.

Doing your best to maintain a proper weight during pregnancy is important, as women who gain too much weight may have to have a C-section to deliver the child, and they also tend to retain more of the weight post-pregnancy. Gaining too much weight can also put you at increased risk for high blood pressure and gestational diabetes. On the other hand, underweight women are more likely to have premature or low birth-weight babies. See our pregnancy weight gain chart below for a visual breakdown of how much weight you should gain by trimester, based on your pre-pregnancy BMI.

Weight Loss During Pregnancy

In the first trimester of pregnancy, it is fairly common for women to lose a little weight instead of gaining it. This first trimester weight loss is usually because of morning sickness.

Otherwise, though, it is not advisable and can be dangerous for you to deliberately try to lose weight during pregnancy. While remaining physically active and eating a healthy diet are both highly recommended, decreasing your caloric intake for the purposes of weight loss can rob your baby of vital nutrients and potentially lead to health problems down the road.

Pregnancy Weight Gain Chart by Trimester

Remember that your weight gain might not be evenly spaced, especially if morning sickness in your first trimester leaves you a few pounds lighter. But while you won't need to gain much weight in your first trimester, adequate weight gain in your second and third trimesters is crucial for your baby's growth and development -- you'll likely need to put on between one and two pounds every week. You can expect your weight to plateau around week 37, when your baby is full-term and your body prepares for delivery.

Your Body Mass Index First Trimester Gain Second Trimester Gain Third Trimester Gain Recommended Total Weight Gain
Less than 19 (underweight) 5 to 6 lbs 12 to 24 lbs 12 to 24 lbs 28 to 40 lbs
19 to 26 (normal) 3 to 5 lbs 12 to 20 lbs 12 to 20 lbs 25 to 35 lbs
27 to 30 (overweight) 1 to 2 lbs 8 to 12 lbs 8 to 12 lbs 15 to 25 lbs
Over 30 (obese) 1 to 2 lbs 5 to 10 lbs 5 to 10 lbs 11 to 15 lbs

Breakdown of Pregnancy Weight Gain

Where Does your Weight Go? How Much of your Total Weight Gain? For a 30 lb Weight Gain
Baby 25% 7 to 8 lbs
Fat Stores 23% 7 lbs
Body Fluid 13% 4 lbs
Blood Volume 13% 4 lbs
Amniotic Fluid 7% 2 lbs
Breast Tissue 7% 2 lbs
Larger Uterus 7% 2 lbs
Placenta 5% 1-2 lbs