Is menstruation a safe period?

Menstruation is a woman’s “good friend” that appears every month. Once this “good friend” is late or painful, it is a very annoying situation. In addition to menstruation, women are also very concerned about the safe period and ovulation period. So, is menstruation a safe period? Actually, it is not. The safe period refers to the 7 days after the end of menstruation. The safe period of each month changes with the menstrual period.

Menstruation is a physiological cycle that occurs in some fertile female humans and in chimpanzees and other animals. Cows, horses, camels, pigs, and sheep also menstruate, and some mammals experience estrus cycles. In women of childbearing age and female primates, the endometrium undergoes cyclical changes every month or so, with autonomous thickening, blood vessel proliferation, glandular growth and secretion, and endometrial collapse and shedding accompanied by bleeding. This periodic vaginal discharge or uterine bleeding is called menstruation.

The female internal reproductive organs consist of the ovaries, uterus, and fallopian tubes. The main function of the ovaries is to produce eggs and synthesize ovarian hormones, while the uterus and fallopian tubes are reproductive organs. The ovaries contain tens of thousands of follicles, each of which contains one egg.

Before puberty, the follicles are essentially non-functional. During puberty, under the action of gonadotropin from the anterior pituitary gland, immature follicles gradually develop and synthesize estrogen. When the follicle matures and ovulates, the follicle wall collapses, the cells become larger and yellower, and are called the corpus luteum. It synthesizes estrogen and produces progesterone.

As the ovaries change, the endometrium is also affected and undergoes corresponding cyclical changes. Estrogen causes the endometrium to thicken, the endometrial cells to increase in number and size, and the arterioles in the interstitium to become more tortuous and spiral, which is called the proliferative endometrium. After ovulation, due to the combined effects of estrogen and progesterone, the endometrium becomes edematous, the glands produce a large amount of mucus and glycogen, and the thickness of the endometrium increases from 1 mm to 6 mm, which is called the secretory endometrium.

If the egg released at this time is fertilized, the fertilized egg is transported to the uterus through the fallopian tube for development, which is called pregnancy. The pregnancy tissue synthesizes a chorionic gonadotropin, which supports the continued development of the corpus luteum of the ovary. If the egg is not fertilized, the corpus luteum will atrophy and stop secreting estrogen and progesterone about 14 days after ovulation. At this time, the blood vessels in the endometrium contract, the endometrium necrotizes and falls off, causing bleeding and forming menstruation.

Therefore, the length of the menstrual cycle depends on the length of the ovarian cycle, which is generally 21-30 days, but varies from person to person, and may be 23-45 days, or even 3 months or half a year as a cycle. As long as it is regular, it is generally considered normal menstruation.