Just before the ovulation phase, the body prepares for a possible conception followed by the reception of the fertilized cell, which is called implantation. This takes place in the endometrium (the lining of the uterus), which grows to about 10 mm in thickness. This can sometimes cause pain and tightness in the lower abdomen. During and just after ovulation, the endometrium continues to grow and create neovessels and can reach up to 14 mm in thickness. Again, the swelling of the endometrium can be very painful. Finally, if conception does not take place, the endometrium suddenly retracts, and the uterine lining detaches and is eliminated through the natural channels: commonly known as menstruation. Again, this process can lead to tightness in the lower abdomen and severe pain. It is therefore normal to feel this kind of discomfort in the lower abdomen after ovulation since it announces the beginning of the period.