Kinda of a "duh"?
Seems to me that you wouldn't want to get pregnant after gastric bypass anyway, but who knows.
The New York Times > Health > Case Offers Caution on Stomach-Stapling Surgery
An obese Massachusetts woman and her 8-month-old fetus died of complications 18 months after the woman had stomach-stapling surgery, an apparent first that is leading to warnings about the risks of pregnancy soon after the surgery.