For life-threatening medical emergencies, call 911 without delay. For a mental health crisis, call or text 988 for free and confidential crisis support.
The cervix is the lower part of the uterus that opens into the vagina.
The endometrium is the mucous membrane that lines the inside of the uterus. The endometrium changes throughout the menstrual cycle. About once a month, it thickens with extra blood vessels. A pregnancy can occur if a fertilized egg attaches to, or implants in, the endometrium. If a pregnancy doesn't occur, part of the endometrium is shed, causing menstrual bleeding.
Current as of:
April 18, 2023
Author: Healthwise Staff Clinical Review Board All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
Clinical Review Board All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.
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