Why during pregnancy menstruation stops?

Menstruation stops during pregnancy because the body is preparing to support the growth and development of a baby. Here's why menstruation stops during pregnancy:

High levels of progesterone: During pregnancy, the corpus luteum (a small gland that forms on the ovary after ovulation) continues to produce progesterone. This hormone helps maintain the pregnancy and prevents the shedding of the uterine lining (menstruation).

Human chorionic gonadotropin (hCG): This hormone is produced by the developing placenta and plays a crucial role in maintaining the pregnancy. hCG stimulates the corpus luteum to produce progesterone and also signals the ovaries to stop releasing eggs (ovulation), thus preventing menstruation.

Thickened uterine lining: The uterine lining, also known as the endometrium, undergoes significant changes during pregnancy. It becomes thicker and more vascularized to provide a supportive environment for the implantation and growth of the fertilized egg (embryo). This thickened uterine lining is not shed during menstruation.

Changes in the cervix: The cervix, the opening of the uterus, also undergoes changes during pregnancy. It becomes softer and produces a thick, mucus plug that blocks the entrance to the uterus. This cervical mucus plug helps prevent bacteria from entering the uterus and protects the developing baby.

Absence of ovulation: Ovulation, the process of releasing an egg from the ovary, does not occur during pregnancy. The high levels of progesterone and hCG prevent the ovaries from releasing eggs, ensuring the focus is on supporting the existing pregnancy.

Therefore, menstruation stops during pregnancy due to the hormonal changes and physiological adjustments that occur to support the growth and development of the baby. Menstruation resumes after pregnancy, typically after the cessation of breastfeeding or the postpartum period.