How long after having a baby can someone undergo gastric byp surgery or lap band surgery?

I was obese before I got pregnant and now i am terrified of living the rest of my life in this fat suit. I am 4' 11" and over 200 lbs. I have been able to restrict my weight gain during this pregnancy to 15 lbs so far. I am only 22 weeks and don't want to put my babys health at risk by dieting.