The same way you deal with any reason for extra weight -- eat a better diet that doesn't metabolize into sugar as quickly and exercise more -- and take it slowly so it stays off. Permanent changes work better long-term than diet fads.
Congrats on your baby! Even through you are a busy mom, don't forget about your needs. Always eat breakfast to jumpstart your metabolism. If possible, get a stroller! You'd be surprised how much walking really does burn. Also, try to avoid late dinners. I don't know what your schedule is like, but it definitely helps to not eat later in the evening. You don't need to put yourself into a harsh restriction though. If you need a late snack, try to keep raw veggie's and hummus on hand instead of chips or something. It might not always be possible (before my husband, I was able to control what food was in my kithen, and now I have to actually choose not to eat his junk food when snacking) but I think most importantly is to take it one day at a time. Don't give yourself too much guilt over the few unhealthy things you eat or if you don't get much exercise once. It's good to set goals, but depriving yourself from anything you really crave will set you up for failure. Hope this helps!