Flat Bum After Pregnancy? – Why You Should Care

Myths of the Postpartum Body: Part 4 of 4

Myth #4: Pregnancy affects abs, not bums.

You may have read my previous posts in this 4-part series on myths of the postpartum body (here, here, or here). As a result, you may think by now that I’m going to say this 4th myth might be true, depending on your body. I’m not.

Pregnancy affects bums BECAUSE it affects abs. Always. For everyone.

I promise to make sense of this, but first, I want to get to the part about why you should care.

Why does it matter if you have a flat bum?

If you’re someone who has already noticed a loss in the shape or function of your bum after babies, then I may not need to convince you that this is important. If that’s you, feel free to skip on down to the next section.

If you’re still reading this, I’m going to assume that you think the shape or function of your bum isn’t a high priority. Here are two research articles to help you reconsider. (There’s a ton more out there. I just picked two, but feel free to keep browsing. There are LOTS.)

The first one demonstrates a link between low back pain in women and the size of the woman’s gluteus maximus. In short, the smaller the muscles of your bum the more likely it is for your back to hurt. This one is for those of you who need to be motivated for the present.

The second one is for those of you who are motivated by what may happen in the future. This article demonstrates a link between gluteal muscle performance and risk of falls in older adults. In short, the less function in your glute muscles the more likely you are to fall. If you don’t know it already, falls are bad news for seniors. Falls can result in broken bones; broken bones can result in decreased mobilty; and decreased mobilty can take years off of one’s life—not to mention quality of life.

So, if you’re not motivated by the way your bum looks in your jeans or by the athletic performance that comes with strong glutes, hopefully, the idea of decreasing pain and improving quality and longevity of life are things that speak to you. Can we agree now that a strong bum is important?

Cool. Let’s talk about how it’s affected by pregnancy, but first, the briefest of anatomy lessons.

A very, very short anatomy lesson on hips


The hip is a ball and socket joint, where the ball is the top of the femur (or thigh bone) and the socket is at the outer aspect of the pelvis.

Unlike the knee or elbow, which are hinge joints, the hip is capable of far more mobility. It can move forward and back—when looking at someone from the side. It can move out and in—when looking at someone from the front. And it can turn inward and outward—when looking at someone from the top down. For the purposes of this discussion, we’re going to focus on the forward and back motions and on the out and in motions. It’s not that the turning isn’t important. It’s just that I’m trying to keep things simple.

There are basically a gajillion muscles all around the hip joint that help it to move in these directions, but the ones that contribute most to the shape of the bum are the gluteals. You can think of them like the big sister (gluteus maximus), the middle sister (gluteus medius), and the little sister (gluteus minimus). This post is really going to focus on the first two. Sorry to any of you little sisters out there.

How pregnancy causes a flat bum

What happens to Gluteus Maximus (GMax)


I think we’re all pretty familiar with what pregnancy does to a woman’s abs—they get super stretched out. Because each muscle has an ideal length, it can’t contract well if it’s too long. This is exactly the scenario when a woman’s abs are stretched over a growing baby. Even if you’re someone who was able to workout throughout your entire pregnancy, you still lost some ab strength. It’s unavoidable because of the degree of stretching. And for most of us, we lost A LOT of ab strength.

We touched on this briefly in Myth #2, but basically, your glutes should be the counterpart to your abs. If they’re not, you’re typically using too much of your hip flexors and your back muscles instead. GMax is the largest muscle in the human body. You need it to work for you. One of its jobs should be to push your pelvis forward when your foot is on the ground. The other is to stabilize your pelvis from the back, so that your abs can pull up on your pelvis from the front.

If your abs aren’t pulling up from the front—because they’re too busy stretching over that gorgeous baby you made—then they’re not giving your GMax something to work against. And if they’re not giving GMax something to work against, then it’s getting weak too. Just like your abs. At least in part, because of your abs.

What happens to Gluteus Medius (GMed)

Although nothing is ever quite this simple, you can think of GMax as stabilizing from the back of your pelvis and GMed as stabilizing from the side of your pelvis. Just as we have already talked about what pregnancy does to your abs, we have also already talked about what pregnancy does to your pelvic floor. If you haven’t read it or don’t have the time right now, your pelvic floor provides an upward stabilizing force for your trunk. When there is a baby filling space inside of your abdominal cavity, it provides its own kind of stability, and this weakens your pelvic floor because the demands on it aren’t as great.

You may be starting to connect the dots by now. But basically, just as GMax works from the back with your abs from the front, GMed works from the outside with your pelvic floor from the inside. They have to balance each other out for your hip to function properly. Pregnancy, delivery, or the postpartum period can cause the pelvic floor to become weak OR overworked, which can then contribute to GMed being weak or overworked. Additionally, if you don’t have a strong GMax, then GMed will try to take over for it.

However you look at it, it’s easy to end up with an unfamiliar soup of hips, abs, and pelvic floor that results in a body that doesn’t work like it did before babies. This translates into workouts that don’t get the same results as before babies. Is this you? Have you felt this way?

How to take your flat bum from pancake to peach

Maybe you’re someone who has struggled for months (or years) to get back the belly or bum you had before babies. Or maybe you’d never given your flat bum any thought before you came across this article. Whichever category you fall into, I hope you can see now why having a bum matters—for more than just aesthetics. And I hope that what seemed to make no sense at all has actually become quite reasonable.

Better function of your pelvic floor and abs can lead to a flatter belly, drier undies, and a better sex life. But they can also improve the shape of your bum, the fit of your jeans, and your athletic performance. And then there’s the parts about decreasing back pain and improving the quality and longevity of your life.

Your bum, your pelvic floor, and your abs all have to work together. You cannot have a fantastic version of any of them without the others. If all of this seems like a lot to consider for a good postpartum recovery—well, it might be. This is at least in part why so many programs work for some women but not others. If you feel like your postpartum body should have come with a user’s manual, then the Mama Made Strong program might be the answer you’ve been looking for.


4 thoughts on “Flat Bum After Pregnancy? – Why You Should Care”

  1. Seth Petry-johnson

    I love these blogs. A little tongue-in-cheek at times and ASStoundingly informative. The anatomy lessons are useful even for us guys 🙂

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