I'm 16 weeks pregnant & i keep getting pains in my lower abdomen like menstrual cramps, no bleeding & the doctors say my baby is fine . what is it?

Could be just pain: As the baby grows, the uterus expands and ligaments on the sides stretch. This can be an explanation of groin like or lower abdomen pain Thie symptoms you describe are similar to what other women have reported. Let your doctor know about your concerns. It isn't always possible to say why someone has pain but your doctor can examine and rule out causes of pain.

Hard to speculate: Much of the discomfort arising in the abdomen comes as a function of digestion.Since many other organs exist in the same space, it is sometimes hard to sort out the origin without doing a physical exam and if possible, identifying an area that triggers the pain. It is good that you saw the doc and baby is okay, for now just monitor things and followup with your doc as needed.