What are the three most common nonobstetric abdominal surgical diseases that present during pregnancy? Their incidence?

1. Appendicitis, 1 in 1,500 - 2,000 pregnancies 
2. Cholecystitis, 1 in 1,600 - 10,000 pregnancies 
3. Bowel obstruction, 1 in 3000 pregnancies 

Source

Dietrich, C. et al.  "Surgical Diseases Presenting in Pregnancy"  Surg Clin N Am.  2008.