The Truth About the Size of Your Pregnancy Belly

Medically reviewed by Janine Kelbach, RNC-OB on January 25, 2016Written by Lisa Baker on January 25, 2016
Pregnant Belly

When it comes to your pregnant belly, there’s no shortage of old wives’ tales telling you what to expect. Your friends and relatives are also sure to have opinions they’re eager to share with you.

But there’s also a good chance that much of the advice you’ll hear during pregnancy about your weight gain isn’t true. Here’s the truth about the size of your baby bump and what to expect.

Weight Gain During Pregnancy

Your doctor will probably track your weight gain during pregnancy. But they may not be as concerned about it as you are. Although there’s a recommended amount you should gain each trimester, keep in mind that the recommendations are averages.

If you were underweight at the beginning of your pregnancy, you’ll probably need to gain more overall. If you were overweight when you got pregnant, then you may need to gain less for your baby bump.

It’s also important to know that tracking and controlling your pregnancy weight gain doesn’t usually improve birth outcomes. So if your weight gain doesn’t meet the averages, look at your diet before you worry about the scale.

Make sure you’re eating healthy food and that you’re listening to your body. Try to eat when you’re hungry, and stop eating when you’re full. If you focus on keeping your diet nutritious, your weight gain should take care of itself.

BMI and Pregnancy

If your BMI is average at the start of your pregnancy (between 18.5 and 24.9), then you should gain between 1 and 4.5 pounds during the first trimester, and 1 to 2 pounds per week throughout the second and third trimesters. That’s a total of 25 to 35 pounds over the course of your pregnancy.

If your BMI was below 18.5 when you got pregnant, then you should gain 28 to 40 pounds. If it was between 25 and 29, then you should plan on 15 to 25 pounds. If it was over 30, you’ll probably gain between 11 and 20 pounds total.

The Truth About How Your Belly Looks

There’s an old wives’ tale that claims the way you carry tells you whether you’re having a boy or a girl. With a boy, you carry it low and out in front, while your girl baby weight is higher and more spread out in your waist. But the facts and science don’t back this up.

In reality, how you carry has nothing to do with your baby’s sex. What does make a difference is how toned your abdominal muscles were prepregnancy, as well as how tall you are.

If you had a six-pack before you got pregnant, you’ll probably carry higher, since your abdomen will support the weight better. If your abs were flabby to start with, you’ll carry lower. Taller women carry more in front, while the weight is more spread out to the sides if you’re short.

When You’ll Start Showing

Every woman starts showing at a different time. Your baby won’t be big enough to show until the second trimester, but many women get a belly in the first trimester from increased water and bloating.

Again, your prepregnancy fitness level plays a factor. Stronger abs means you’ll keep your flat belly longer. Whether you’ve been pregnant before is another predictor — second and subsequent pregnancies show sooner. That’s partially because your muscles are weaker from previous pregnancies.

Measurements

Your doctor will probably measure your belly at prenatal visits, starting around 20 weeks. This is to make sure your belly bump is on track. It’s just another way of checking your baby’s growth. It’s also a way to check your due date if you’re not sure of the date of conception.

Everyone carries differently, so you usually don’t need to stress if your measurements are a little off.

On average, you’ll gain about 1 centimeter per week between your pubic bone and the top of your uterus. If your measurements are off, your doctor might suggest an ultrasound to make sure baby’s growth is on track.

The Takeaway

For many women, pregnancy weight gain is hard to accept. If you’ve worked to be at a healthy BMI most of your life, it’s a big shift to suddenly worry whether you’re gaining enough weight.

Fortunately, weight gain doesn’t need to be cause for concern for most women. As long as you’re eating healthy and following your hunger cues, most of the time your baby belly should stay right on track. 

Lisa Baker
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