M.
Updated to add: Though pilates is a great thing, *BEWARE* until after you've closed your diastasis!!! First, you must work the transverse exclusively and gently to close the gap, and then once you've done that, go on and have a great time with pilates. However, doing "The Hundreds" (and other types of exercises) before your diastasis is closed can really exacerbate the problem. At physical therapy, I had to use a splint around my waist to manually hold my rectus abdominus closed *before* I was allowed to even do a mini-crunch (just lifting my head - not my shoulders, just my head!). So... be wary of any fitness programs that aren't specifically tailored to your diastasis. Also, if you are carrying any babies or toddlers in front carriers (like the baby bjorn or a sling or a wrap), get a splint to wear during the times you're carrying (again, until your diastasis is resolved).
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S., your NP is the one who is absolutely *wrong* here - you are not crazy, you are quite astute!
I had the same thing - it is called a diastasis. Many, many women have this, though the gap can be as small as 1 finger (so not terribly noticeable) or as wide as 5 or more fingers. Mine was 4 fingers wide, and I did go to postnatal physical therapy for it - got it down to 2 fingers wide, but I think if I were more devoted to continuing the exercises, I could reduce it even further.
The PDF link that one of the other moms suggested is excellent - it talks about Julie Tupler's book & DVD called "The Mummy Tummy." I definitely recommend the book which is very thorough, discusses how to self-diagnose your diastasis, describes the necessary exercises, shows pictures of the exercises. I have the DVD as well, and if I had to choose, I probably would just get the DVD instead of the book:
http://www.sobebabies.com/shop/index.php?main_page=produc...
Tupler first suggests to work on strenghtening the transverse muscle by doing seated transverse "elevator" exercises as described in the 2nd column here:
http://www.maternalfitness.com/baks_basics.pdf
You can definitely have a diastasis many, many years after giving birth - it will stick around until you do the exercises to fix it! Your NP is clearly not educated on the topic of diastasis, and based on her reaction (refusing to check you?!?!), I would avoid her for future care in general... for me, it is important that my care providers take my concerns seriously and have enough intelligence to recognize when they might not know all the answers and might have to do a little more research. There is nothing wrong with saying "I do not know, but I will do some research and get back to you."
Good luck!