What Is Diastasis Recti, and Why Does It Happen During Pregnancy?

After welcoming twin boys Asher and Aksel in November 2019, pro volleyball player Morgan Miller, who is married to former Olympic skier Bode Miller, has shared one fairly common—but not often talked about—consequence of pregnancy and childbirth. On her Instagram page, Miller revealed that she's suffering from diastasis recti, which is the separation of the abdominal muscles.

Even 14 months postpartum, her abs are still separated, and she showed her followers what it looks like—a noticeable dent down the center of her stomach—and how she's helping her body recover.

"The twins did a number on my stomach," Miller wrote. "And after being a professional athlete where my body was my vessel in which I was able to perform the massive changes (including diastasis) was hard for me."

What Is Diastasis Recti?

During pregnancy, the linea alba, the central seam of the abdomen, thins out in order to accommodate the growing uterus, says physical therapist Patricia Ladis PT, CBBA, co-author of The Wise Woman's Guide to Your Healthiest Pregnancy and Birth. "In some cases, it doesn't resolve after pregnancy," Ladis tells Health. "You can feel a bulge, doming, or may see a gap between your right and left abdominal wall muscles."

While 100% of pregnant women experience this stretching, and most of them find that it resolves without intervention (sometimes as early as 12 weeks postpartum), about 30% of women have a diastasis problem after pregnancy, Ladis says.

What a diastasis recti isn't is an actual tearing of the abdominal seam. "This is a misconception," Ladis says. "First, the abdominal seam doesn't actually tear into two halves: it stretches and widens so that the two sides of the rectus abdominis muscles are farther apart."

Importantly, the width of the stretch isn't as important as the depth and your ability to generate, or not generate, tension. "You can still generate tension to support yourself with your core even if you have a mild diastasis," Ladis notes.

Why Do Some Pregnant Women Get It, and Others Don't?

Basically, it's just one of the side effects of pregnancy. But if you have strong collagen (the primary structural component of connective tissue), this will help the linea alba thicken after delivery and generate the appropriate tension to restore the abdominal wall, Ladis explains. "However, having good collagen is genetic—if you have thin skin, which can look more transparent or bruises/tears after minor injuries—you may produce less collagen," she says. "When you produce less collagen, you have a greater chance of not fully restoring pre-pregnancy-tension in the linea alba."

Having more than one child makes this condition more likely, especially if they're close in age. The risk of diastasis recti is also higher if you're over 35 when you get pregnant, or if you're expecting a heavy baby or multiple babies.

How Do You Know If Your Abs Have Separated?

The most obvious sign is a bulge in the middle of your abdomen, Christine Greves, MD, an ob-gyn at Orlando Health in Florida, tells Health. Sometimes, it may not be noticeable unless tension is created, such as through coughing.

You can use your fingers to help determine whether or not you have it. "When feeling the vertical line above or below your navel, there may be some separation," Dr. Greves explains. "If you can fit one or two fingers in between it, that is usually normal. However, three or more fingers could be a sign that you have diastasis." More than 2cm—a little more than half an inch—is abnormal.

Exercise Can Reverse a Diastasis

Many people turn to exercises to reverse the condition: It's all about adapting better core function, along with correct diaphragmatic breathing, Ladis says. However, you'll have to stick with the right exercise program to make a difference. You won't see real results immediately.

"A physical therapist specializing in women's health can measure your diastasis and help you identify the best cues and exercises to generate tension and/or close the diastasis," Ladis says.

For Miller, that involved "a lot of PT work and very basic pilates" from two weeks postpartum, she wrote. She stressed the importance of doing exercises correctly by engaging the ab muscles and the pelvic floor. For example, when she does crunches, she makes sure her stomach goes inward, creating the dent, rather than outward, which causes a raised line down the middle and puts more strain on her stomach.

Ladis says getting the diastasis to close and firm up isn't about pushing or strengthening the abdominals more, Rather, it's about coordinating the deep abdominal system to bring the tissues together to produce positive, supportive tension. "It's important to avoid activities that create pressure through this area, which can stretch the linea alba further or decrease your connection with the muscles that can support you again," she explains. "This includes curl ups, sit-ups, or abdominal exercises where you lift your head off the floor when lying down on your back, or hover your legs parallel to the ground."

It's also important to be aware that it may take up to 18 months for your collagen to realign to close the gap. After this time, if you can't produce good abdominal tension to support your back and pelvis, you may need to consider surgery, Ladis says, especially if the diastasis remains larger than three fingers in width.

As well as the exercises recommended by your physical therapist, Dr. Greves advises avoiding lifting heavy objects (including carrying your baby on one hip) and concentrating on having good posture.