Final answer:
Uterine pain and significant bleeding occur in the first trimester of pregnancy.
Step-by-step explanation:
Uterine pain and significant bleeding occur in the first trimester of pregnancy.
In the first trimester, the fetus is in its early stages of development and is attaching to the uterine wall. The rapid growth of the fetus and the adjustments of the body can cause pain and bleeding.
It is important to note that any pain or bleeding during pregnancy should be evaluated by a healthcare professional to ensure the well-being of the mother and the fetus.