I wrote this in the hope that it will benefit someone who reads it. So what really is menstruation? why does it occur? what happens during menstruation? These are questions a lot of men and a few women - i guess - on nairaland want answered. In answering some of these questions, I have neglected the unnecessary technicalities (the endocrinology is extremely complicated) which will only confuse the entire thing.

First off, a little about female reproductive anatomy:

Basically, all the female reproductive organs are either a part of the external Instruments or the internal Instruments. The external Instruments also called the vulva (which isn't important in this discussion) includes the following: mons pubis, labia majora, labia minora, vestibule and vestibular glands, and the clitoris.

The internal Instruments include the vagina, the uterus, a pair of fallopian tubes, a pair of ovaries. For the purpose of this discussion, please bear in mind that the ovaries contain little eggs in them. At birth, there are about 2 million eggs but almost half of these number are and will remain non-functional.

Why does menstruation begin when it does?

By the time a female baby is born, all of her reproductive organs (both external and internal) have been completely formed but menstruation does NOT occur, because before puberty, the necessary hormones needed to trigger menstruation are produced in extremely minute concentrations.

At puberty, there is a marked increase in the level of these hormones and they begin to have varying effects on the entire female body including the external and internal Instruments. So besides the development of the Instruments, they also "kick start" menstruation.

What is the purpose of menstruation?

Well, without it, the woman won't be able to conceive.

What about cycle length?

Cycle length varies from woman to woman but generally it is 28 plus or minus 7 days (normal range is 21 - 35 days). A cycle length is the time from the 1st day of one period (the very first day blood started flowing) up till the 1st day of the next period.

What happens during menstruation?

Many things happen but basically things that happen take place both within the ovaries and the uterus (or the womb). In the following explanation, I will assume that the woman has a 28 day cycle:

Ovarian Cycle: Within the ovaries, the important activities are:

Phase 1: Period of egg growth (scientifically called the follicular phase) - On day 1 of every cycle, 5-15 eggs within one ovary begin to grow but only 1 will reach full maturity. The others will regress and will remain non - functional. This phase occurs from Day 1 of the cycle up and by Day 14 when these phase ends, there is 1 mature egg within the ovary. 

IMPORTANT POINT TO NOTE: Please understand that the end of one phase marks the beginning of a new phase, that is why Phase 1 lasts from Day 1 to day 14, phase 2 occurs on Day 14 while Phase 3 begins on Day 14 and ends on Day 28.

Phase 2: Period of mature egg release (scientifically called ovulation) - So now that 1 egg has reached full maturity, it isn't doing anyting within the ovary, so it is expelled via a process called ovulation. In some women, this process is associated with pain (called a mid- cycle pain). The mature egg is released from the ovary and then enters the fallopian tube and REMAINS there - waiting for sperm.

Note the following:

Note that a woman has a pair of ovaries and fallopian tubes but most times, only 1 mature egg is released from one ovary (just imagine that the ovaries take turns in releasing a mature egg). There are certain instances when both ovaries will release a mature egg and both of them may or may not become fertilized by sperm. If fertilization does occur under this circumstance, it results in the birth of non-identical twins.

Phase 3: Called the luteal phase: Before the mature egg was released from the ovary, it was protected by a fence of cells but during the process of ovulation, this surrounding fence of cells was left behind inside the ovary. During this luteal phase, the fence of cells develop into what is called a a "corpus luteum" that begins to produce progesterone.

Uterine Cycle

So where does the blood come from, to understand we have to look at the Uterine Cycle. It also has 3 phases that correspond to the phases of the ovarian cycle.

Phase 1: Menstrual Phase. Occurs from Day 1 - Day 5 of the cycle. In many women however, the period of bleeding varies between 2 and 8 days. We'll talk about what happens here later on.

Phase 2: Called the follicular phase. Unlike the follicular phase of the ovarian cycle, that of the uterine cycle begins from Day 5 of the cycle and ends on Day 14 of the cycle.

Before going on, let me mention that the uterus has 3 layers: an outer layer of protective covering (perimetrium), a middle layer of thick muscle (myometrium), and an inner layer (endometrium). The endometrium is in turn made up 2 layers of cells. An outer layer and an inner layer.

Okay, so during the follicular phase, certain hormones from some part of the brain begins to stimulate the cells of the endometrium so they begin to gradually increase in number and size. During this phase, the growth of the endometrium is stimulated by estrogen.

What is the fertilizable period of a mature egg released during ovulation?

The answer to this is simple. Remember we said the mature egg is released from the ovary and goes into the fallopian tube waiting for sperm to fertilize it. After its release from the ovary, the mature egg will remain fertilizable (or fertile if you would call it that) for 24 hrs after which, it can no longer be fertilized by sperm.

Phase 3: Called the secretory phase. Remember that ovulation was on Day 14 and after this time, the fence of cells left within the ovary began to produce progesterone in increasing quantity. Well, the progesterone produced by the corpus luteum within the ovary stimulates cells of the endometrium and they begin to further increase in size and make the endometrium "more suitable" for the implantation of a fertilized egg (whether or not conception occurs).

Please note again that the corpus luteum can only remain alive for 9 days after ovulation (from Day 14 up till Day 25). After this time, they die off and so progesterone production stops.

Phase 1: Back to menstruation. Progesterone is a chemical that has so many fascinating properties including:

* blocks the production and release of the chemicals that cause menstruation ie. prostaglandins (responsible for the pain women feel during menstruation)
* keeps the muscle of the uterus in a relaxed state
* is thermogenic (that is, it causes a rise in body temperature)
* others

As from Day 25, the amount of progesterone present in the system begins to decrease markedly  while levels of prostaglandins that cause menstruation will steadily be on the increase. The prostaglandins cut off the blood supply to the innermost layer of the endometrium - poor blood supply means the cells present in that layer are killed. By Day 1 of the new cycle, the cells of this inner layer of the endometrium are shed off together with some of the blood that escapes from blood vessels underneath as menstrual blood.

Basically, we say that phase 3 of the uterine cycle begins on Day 14 and ends on Day 1 of the next cycle.

All of the above repeats itself in the next cycle.


What is the Menstrual Cycle?

The menstrual cycle is a term that refers to both the ovarian and uterine cycles.

Safe and Unsafe Periods?

Safe period are basically those days during the menstrual cycle when you can have unprotected sex without the risk of pregnancy. There are 2 sets of safe period in the menstrual cycle - a period before ovulation and then after ovulation.

Before ovulation - You want to exclude Day 1 - 5 or any of the days when the woman is bleeding and then you also want to exclude 3 days before ovulation. Why? Because when sperm enters the woman, they remain alive and active for an average of 2 - 3 days after then. So therefore, before ovulation, the safe days are Days 6,7,8.9. and 10.

After ovulation - You want to exclude 2 days after ovulation so you can definitely be sure that the egg is now unfertilizable. So safe days are Days 17,18,19,20,21,22,23  up till the last day of the cycle.

The use of safe and unsafe periods as a form of contraception is called the RHYTHM METHOD. The major drawback with this method is that you must be sure of the ovulation day.

Determining which day is the ovulation day?

This is critical for the success of RHYTHM METHOD and its very easy to do this.

Remember that the cycle length varies from one woman to the next but fortunately, the time from the day of ovulation to the 1st day of the next cycle is ALWAYS, i repeat ALWAYS, 2 weeks.

With this fact in mind, I guess it becomes very easy to calculate your date of ovulation once you know your cycle length and it is relatively constant from month to month. There are many factors that may make the cycle length vary from month to month but that is beyond the scope of this write up but 2 important are: emotional factors and use of oral contraceptive pills.


I do hope someone has gained immensely from this write up and not be confused about whether or not pregnancy can occur during menstruation?

Regards,
--fsb--

Arrrrrrrrrrrrrrrrrrrg, lol, why remind me?

lol!!!

Thanks for the great job

interesting thread.

^^^ thanks for resurrecting the thread

Thank u .....i really learnt from this

Uniquefm:
Thank u .....i really learnt from this

long live to u n many happy returns

happy brthday