Be careful while you raise yourself from a sitting or lying position. Do not be spontaneous in your actions. Try to be careful in what ever you do. Give support to yourself.
Try to practice kegel exercise. Kegel is a popular prescribed exercise for pregnant women to prepare the pelvic floor for physiological stresses of the later stages of pregnancy and vaginal childbirth. It helps in giving strength to uterus, pelvis etc.
If you feel that you are not interested in sex, then please avoid it.
Keep a small pillow for support of stomach to make yourself comfortable.