My pregnant wife (3rd trimester) has a pulse on her stomach which appeared randomly and has now suddenly stopped, is this normal? what could it mean?

"3rd TM pregnant" ?: In the third trimester of pregnancy, the pressure of the uterus and growing fetus especially after a maternal meal may cause expansion of the intestines with food, and compression of the aorta passively, and be detectable as a "pulse" on the stomach area. As the food is dispersed by digestion or passage into the lower intestines, this would stop the "pulse". See your OB to be certain.