Almost all women have some cramping or other pains during pregnancy, particularly in the first trimester. This cramping is almost never anything to be worried about, particularly if you’re not bleeding. In the first trimester, the uterus grows rapidly and most of the cramping that a woman experiences is simply growing pains. As the uterus gets bigger, it becomes top-heavy and has a tendency to pull and tug from one side to the other. This will stretch ligaments, particularly the round ligaments, and cause either cramping or sharp pains. None of these symptoms put the baby at risk.
Sometimes cramping is not related to your uterus at all. Many women become constipated during pregnancy in the cramping that they experience is actually related to their bowels slowing down. Sometimes cramping is related to the bladder and might be a sign bladder infection, but almost always there will be other symptoms like burning when you pee.
In the second and third trimesters, cramping is often what’s cold Braxton-Hicks contractions. These are common and occur more often in subsequent pregnancies. They do not increase your risk of preterm labor.