Sexual intercourse is a kind of mechanical stimulation that can cause congestion in a woman’s vulva, pelvic cavity, and reproductive organs. When a woman becomes sexually excited, through the reflection of the nerve endings around the vagina and cervix, the perineum, vagina, pelvic muscles, and uterine muscles undergo involuntary rhythmic and strong contractions, resulting in abdominal pain.

Sexual intercourse stimulates uterine contraction, which is also closely related to prostaglandins. Because the E and F families in prostaglandins have a strong excitatory effect on the pregnant uterus and can stimulate uterine contractions. During sexual intercourse, the uterus is mechanically stimulated, which causes the release of endogenous prostaglandins in the uterus through nerve reflexes and body fluid regulation. In addition, the man's semen contains a large amount of prostaglandins. Under the action of prostaglandins from both men and women, the uterus undergoes a strong contraction, causing the woman to feel abdominal pain after intercourse.

The contraction of the uterus will not only make pregnant women feel abdominal pain, but may also cause miscarriage, premature delivery, premature placental detachment, premature rupture of membranes, etc., thus endangering the health of the mother and baby. Therefore, obstetricians and gynecologists remind expectant fathers and expectant mothers that it is not advisable to have sexual intercourse in the early and late stages of pregnancy, and that sexual intercourse should also be restrained in the second trimester. Once abdominal pain occurs during intercourse, it is forbidden to share a room.