It’s normal to gain weight during pregnancy. Not only do you have a little one growing inside of you, but you also have the physical changes that come with it. The growth of your uterus, the development of the placenta, a rise in blood volume – all these changes and more contribute to an expected increase in weight.

Healthy pregnancies depend on this new weight for babies to grow and develop properly. But how much weight should you expect to gain during your pregnancy? When’s the right time for that weight to show up, and what’s needed from your diet to make sure you have enough? We’ll show you how to figure out how much weight you need, when to expect it by each trimester, and what to do (and not do) as your body prepares for your new arrival.

Start with your pre-pregnancy BMI to see how much weight to gain during pregnancy

The right amount of weight to gain centers around your pre-pregnancy body mass index, or BMI. Calculated from your weight and height, your BMI gives you a good idea of how much body fat you have. From there, you can see how much more weight you need to gain during a healthy pregnancy.

It’s easy to find your BMI: Just use the adult BMI calculator from the Centers for Disease Control and Prevention (CDC). You can also ask your doctor for your BMI from your most recent visit or refer to your after-visit summary.

Once you have your pre-pregnancy BMI, you can get a better idea of how much weight you should gain during pregnancy.

Recommended total pregnancy weight gain for one baby

BMI below 18.5 (underweight)

If you’re underweight, you'll need to gain a good amount of additional weight for a healthy pregnancy. The CDC recommends gaining 28 to 40 pounds, both for your own health and to help your baby be born at an ideal weight.

BMI of 18.5 to 24.9 (normal weight)

This is a good start! You’re in a healthy BMI range that doctors and specialists recommend. For additional weight, you’ll want to gain another 25 to 35 pounds over the course of your pregnancy.

BMI of 25 to 30 (overweight)

If you’re in this group, you don’t need to gain as much weight for your pregnancy. But you should still add a recommended 15 to 25 pounds to provide enough nourishment for your body and baby.

BMI above 30 (obese)

In this group, it’s important to keep in mind that gaining additional weight is still crucial for a healthy pregnancy. But you’ll only need an additional 11 to 20 pounds. (Also, pregnancy is not a good time to consider losing weight – hold off until after your baby is born.)

Pregnancy weight gain for twins or multiples

If you’re pregnant with twins, you’ll need to gain more weight to account for the second baby to come.

Recommended total pregnancy weight gain chart for twins

If you’re expecting triplets or more, you’ll want to talk to your doctor for a weight gain range that’s personalized to your current health and history.

Pregnancy weight gain usually starts after your first trimester

Most of the weight gained during pregnancy starts to arrive as your first trimester ends, though you’ll still gain a few pounds early on. During the first three months, you can expect to only gain about 1 to 4 pounds, regardless of your pre-pregnancy BMI.

When you start your second trimester, you should start to see an average weight gain of 0.5 pounds to 1 pound per week, depending on your pre-pregnancy BMI. Doctors recommend you maintain this slow and steady gain through the end of your third trimester, ending at your ideal weight.

Recommended weight gain chart by trimester

That additional weight you’re gaining comes primarily from the food you eat during pregnancy. But even though you’re now “eating for two,” you shouldn’t increase your diet by a large amount of extra calories. In fact, doctors recommend an increase of only 300 calories per day, starting with your second trimester – that’s more than enough to make sure your body provides everything your baby needs as it grows and develops.

Should I ever lose weight during pregnancy? What about losing weight after pregnancy?

Even if you start your pregnancy overweight, or if you gain more pregnancy weight than what’s recommended, it’s never good to lose weight before you give birth. Your baby depends on a stable environment while it develops, and actively trying to lose weight can increase risks. In fact, you should call your doctor if you find that you’re losing weight at any time during your pregnancy.

After your baby is born, your body should slowly lose the weight that you’ve gained. Plus, if you combine healthy eating with regular activity during your pregnancy, you’ll be able to lose your extra weight faster after your pregnancy.

The extra weight may seem like a lot for a little baby, but there’s more to your additional pounds than your new arrival. For example, here’s what makes up an average 35 pounds of weight gain during pregnancy:

• Baby: 8 pounds
• Placenta: 2-3 pounds
• Amniotic fluid: 2-3 pounds
• Increased breast tissue: 2-3 pounds
• Increased blood supply: 4 pounds
• Increased fat storage: 5-9 pounds
• Uterus growth: 2-5 pounds

A good amount of this weight is delivered along with your baby, and more will go away gradually over time.