Is it possible to pull a muscle in the stomach during pregnancy?

Yes: Yes you can pull an abdominal muscle while pregnant.

Yes: It is possible for a pregnant woman to "pull" one of the long strap-like abdominal wall muscles. If unclear if labor or if it occurs because of a fall, she should notify her physician especially if she has vaginal bleeding, a discharge, cramping or change in pain or fetal movement. The fetus is usually safe surrounded by fluid in the amniotic sac but sometimes there are problems that are urgent.