What Is a B Belly During Pregnancy and Why Does It Happen?

When you imagine a pregnant body, you might think of a sweet, round little bump. Yet many people who have been pregnant will tell you they felt swollen and larger all over, and that bumps come in a variety of shapes and proportions.

No matter your pre-pregnancy body type, every baby bump is individual in when it appears and how it presents. The perfectly rounded bump you envision might be exactly what you get—or it could look quite different.

But what if your bump appears to be two separate bumps? Should you worry if there’s a band across your abdomen? You may have heard of a “B belly” pregnancy — but what does that term actually mean?

What is a B belly during pregnancy?

A B belly in pregnancy describes a bump that seems to have a crease or waistband across the middle, making the abdomen look split into an upper and lower portion, much like the uppercase letter “B.”

It’s important to point out that your fuller pregnancy breasts are not considered the top of the B! If that were the case, nearly everyone would have a B belly during pregnancy.

The B belly differs from the more typical D-shaped belly, which resembles a capital “D” and lacks a dividing line. Some people call the B belly a double-bump pregnancy.

What causes a B belly?

There isn’t a single definitive cause of a B belly. This presentation is more frequently seen in people with higher body weight, but it can occur at any size or shape. A combination of personal factors — such as height, weight, muscle tone, and bone structure — all influence how a pregnancy bump is carried.

Factors that may contribute to a B belly during pregnancy include:

Your fascial health

“Fascial health” refers to the condition of the connective tissues just under the skin, which help determine belly shape. Fascia can be affected by a sedentary lifestyle, inadequate hydration, poor posture, an imbalanced diet, stress, and muscle injuries.

Previous pregnancies or an inherent fascial structure can also create a divided appearance to your pregnant belly.

To support healthy fascia during pregnancy, try regular stretching, staying well-hydrated, and incorporating gentle activities like yoga or cardio into your routine.

Your body size and weight

According to the commonly used BMI categories, a body mass index of 25–29.9 is considered overweight and a BMI of 30 or higher is considered obese. People who begin pregnancy with higher weight are more prone to developing a B belly, though it’s not certain.

Where you carry weight also matters, since body shape is highly individual.

Your prior pregnancies

Many people notice that after a first pregnancy their abdominal muscles feel looser and their shape can expand more quickly in subsequent pregnancies.

These changes can contribute to a B belly—especially if pregnancies are close together or your body hasn’t fully returned to its pre-pregnancy form before conceiving again.

Your usual belly shape

If you typically have an apron belly or tend to store weight in your midsection (rather than hips and thighs), you may be more likely to develop a B belly even if this is your first pregnancy.

Are there concerns about a B belly?

A B belly by itself usually isn’t a medical concern. However, if higher body weight is a contributing factor, your provider may want to address related health risks.

Health concerns

People carrying more weight face greater risks for:

• Gestational diabetes. This condition can increase the chance of cesarean delivery and may require dietary changes or medication during pregnancy.
• Preeclampsia or elevated blood pressure. These issues can lead to swelling and harm to important organs such as the liver and kidneys.
• Miscarriage and stillbirth.
• Back pain during pregnancy.

The baby of a parent with a higher BMI also has increased risk for complications including:

• Larger size at birth, which can cause injuries or delivery challenges.
• Preterm delivery, which may bring complications affecting organs like the heart, lungs, brain, and gastrointestinal system.

Because being either over- or underweight adds pregnancy risks, it’s important to monitor weight gain and distribute it appropriately across your pregnancy.

Per the CDC, someone who is overweight before pregnancy should aim to gain 15–25 pounds when carrying one baby. If they have obesity, the recommended gain is 11–20 pounds.

How might that look during pregnancy? In the first trimester, expect about 2–4 pounds of gain. After that, a steady increase of roughly half a pound per week for the remainder of pregnancy is a reasonable target.

Emotional concerns

There can also be emotional challenges when your belly differs from what you anticipated. This experience can affect anyone, regardless of shape or size.

Whatever emotions arise, it’s helpful to remember they’re normal and you aren’t alone.

If others make thoughtless or hurtful remarks about your body, lean on resilience strategies like visualization and support from friends. Keep in mind that every pregnant body is distinct, and yours is doing important work to nurture your baby.

Be your own advocate during pregnancy. Celebrate milestones and try to find moments of joy whenever possible.

Is there anything you should do for a B belly during pregnancy?

Fortunately, you don’t need to take special measures if your bump forms a B shape. While it may look different from your expectations, it’s generally a normal variation and doesn’t require correction.

Remember your belly can shift as pregnancy advances. From trimester to trimester, many bumps change in form and size. Some people notice that as weight redistributes, the “B” becomes less noticeable or even evolves into a “D” shape.

Because back pain can accompany pregnancy (depending on the B belly’s causes and other factors), you might appreciate added comfort and support. Maternity support bands can help with comfort and may smooth the appearance of a B belly.

Comfortable, well-fitting maternity leggings or clothing that offer support for your bump can also make a difference. Wearing clothes that flatter your shape can help you enjoy your pregnancy more.

Takeaway

You might hope for an effortlessly simple pregnancy with the perfect cute bump, but reality doesn’t always match expectations.

If your bump looks like the letter B, know you’re not by yourself. Your bump may change throughout pregnancy, and even if it doesn’t, it’s not necessarily something that needs fixing.

While B belly pregnancies are not abnormal, if you notice anything concerning, talk with your healthcare provider. And remember during difficult moments that your baby bump is temporary — your child will be with you for many years to come!