If someone corset trains would it effect her if she get pregnant down the road?

Not enough data: Aside from Victorian times, we don't really have much data on corset (waist) training to give you a cogent answer. Since you're not making any orthopedic changes, probably not, but ya never know! Check out http://www.ebony.com/style/getting-waisted-the-dangers-of-corset-training-897. For a positive perspective, check out http://goo.gl/0fwQUd. Whatever you decide, do it for you, not your partner