Symphysis Pubis Diastasis - the Diastasis no one tells you about!
Also known as pelvic girdle pain, it happens when the ligaments around your pubic bone relax a little too much and can cause a separation of joint without fracture. It happens to many women during pregnancy, but can also happen as a result of vaginal delivery (this, in my case.) It's not made any better when you deliver a baby that's almost a pound bigger than the one who separated the joint last time (this, also my case!)
What's around my hip in the photo (and not my belly, as you can see, it's still stickin' out there right on top of this splint) is actually a hip binding band. It's stiff, and even though most of them claim to "shrink your hips back to pre-pregnancy size" and a bunch of other bs, this is actually just holding my separated pubic bone more comfortably together while I'm upright, hopefully aiding in fusing that gap again.
Splints and belly bands make a ton of false claims, but they all have their place to help you. 3 years ago I bought this one after having a terrible sensation near my pubic bone about 10 days postpartum, accompanied by a ton of pressure, a pinching sensation after peeing, and severe, radiant pain when sitting on hard surfaces. My doctor recommended I use one of these, letting me know that it "can help" (note the word CAN, not WILL) the bone heal a bit better and provide support while it does. Luckily I had it around, because on day 10 post delivery, like clockwork, BAM. All those symptoms came back. It helped last time, and while it's pretty uncomfortable and not the most flattering thing, it does help me, and makes walking a lot more enjoyable.
SPD can make certain exercises uncomfortable, specifically anything where your legs are split, like a lunge. Some women even find squats uncomfortable as it opens up the pelvis, creating more space where we’re trying to close it! For the time that you’re affected by this, avoid any standing split leg movements (single leg deadlifts, leg lifts with bands, sometimes even the flamingo exercise can aggravate this) and focus on bilateral movements that strengthen your glutes and hips.
And one last note on spliting. It's not a splint meant to be used to literally shrink your hips. Splints work with your pregnancy and postpartum period the same way they do with every other part of your body: they are designed to SUPPORT and promote healing while you STRENGTHEN the area around it so the splint becomes obsolete for you.
See that last part? It takes work on your end, too. Just like an ankle sprain takes care and splinting, you would do your PT and your rehab exercises to get the ankle strong again so you can lose that brace as you pick up running again. Your goal with any splint is to eventually deem it useless.
SPD can be painful and frustrating but know that it doesn't last forever! Once those initial postpartum hormones start to ease off, the pain will get a bit better. It can be a rough 4th trimester with it, but pelvic floor PTs, splinting, and pelvic floor rehab exercises are all extremely helpful on your road to recovery!