Well it could be chemistry, expired film, or underexposure. Seriously, it looks like expired film to me. Film that is too fresh (not aged) is usually green. Film that is too old (or perhaps stored in a warm place, or exposed to airport x-rays) can have odd color shifts. I shoot a lot of Astia and it never looks like this.
Here's some ways to test it. If you have more of the same emulsion, shoot a test roll (BTW, make sure you don't have some kind of pink filter on the lens). Try some frames under similar lighting, with a direct flash on camera, and also outdoors (just to make sure its not the lighting - I don't know your light source), Also, when you shoot indoors, make sure you don't have some strong pinkish colored wall nearby that could be infecting your shot with color as the light bounces around the room.
Take your film to a different lab and have it run. If it comes out looking the same, its the film. If it looks good (normal), try another test roll (same emulsion) and this time take it back to the first lab and have it run. If it still looks bad, its their chemistry. If it looks good at the second lab, and then looks OK when you go back to the first lab, I'd still say chemistry, but they've probably fixed it (it does happen). Ask them. Most labs will own up to it unless they think you're going to try and sue them, although most claim they're only liable for replacement film & processing. At the very least, they'll process some rolls for free.
Its not likely to be underexposed because first of all, it would be dark. Second, if it was dark and you pushed it, even three stops (which I've done) you wouldn't have that kind of color shift.
You know, I see a soft black arc shaped pattern on the front of her skirt, this looks like a kink in the film (a light leak would be a white or yellow mark) which would inhibit that part of the film being processed enough. If that'd wha I see, I'm betting its a bad lab. They kink film when they load it, and run it in exhausted chemistry.
If you don't have more of the same emulsion, go back to the camera store and see if you can get some more. (Look to see where they store the film. Hopefully in a refridgerator and not on a shelf facing the sun). The emulsion number is on the film box and on the edge of your processed film, next to the sprockett holes, you'll have to open the mounts to see it. If you can't find any more of the same emulsion, do the tests anyway, and if everything looks fine, it was probably a one-time event. It always helps to test your emulsion when you can, always buy from reputable sellers, and use a good lab.
Good luck, let us know what you find out. Like I said, I shoot a lot of Astia. This is what its supposed to look like (also gray seamless).
model: Jaime Bergman
Andy Pearlman Studio