Small bowel obstruction (SBO) is a recognized complication of Roux-en-Y gastric bypass (RYGB) surgery. Internal hernia (IH) a potential problem associated with RYGB, can have severe consequences if not diagnosed. We present two cases of SBO due to IH during pregnancy after laparoscopic RYGB (LRYGB). Both patients underwent an antecolic, antegastric LRYGB. In both patients a Petersen's type IH was found. We reviewed the cases reported in the literature of SBO during pregnancy after RYGB. IH should always be ruled out in pregnant patients with previous RYGB and abdominal pain. Prompt surgical intervention is mandatory for a good outcome.