Fertility 101: Lesson 02 - Menstrual Cycle and Period

LESSON 03: THE BIG O - OVULATION>>

To avoid any confusion let's first define words:

• Your period or 'menstrual period': Vaginal bleeding observed on average every 28 days lasting on average 3-5 days and following on average 14 days after ovulation if no pregnancy occurred.
• Your cycle or 'menstrual cycle': A time period between the first day of your menstrual period and the day before the next menstrual period.                                                    

The menstrual cycle has four stages:

1. The Menstrual Phase or Menstrual Period
   When a women is having her period, when she is bleeding, the lining of the uterus is breaking down and slowly flowing out of her body through the vagina over a period of days called the menstrual period or menstrual phase. Menstruation is the term given to the periodic discharge of blood, tissue, fluid and mucus from the reproductive organs of sexually mature females. Bleeding usually lasts from 3 -5 days each month, and is caused by a sudden reduction in the hormones, estrogen and progesterone when the egg was not fertilized. For most of a woman's life, the egg that is released approximately once each month will not become fertilized, so the lining that develops each month for the possibility of a fertilized egg cell won't be needed. Over a period of days the blood vessels shrink and the uterus will shed the unneeded lining, made up of a small amount of blood and tissue.
2. The Preovulatory Phase
   The preovulatory phase (before the egg cell is released) is next and starts as soon as bleeding (the menstrual period) has ended. During the preovulatory phase the uterine lining thickens with an increased numbers of blood vessels. The lining of the uterus needs to prepare itself for the possibility of supporting a fertilised egg. An egg is also ripening in one of the ovaries in preparation for ovulation.
3. The Ovulation Phase
   The third phase is the ovulation phase at midcycle, which in a 28-day cycle would be day 14. During ovulation a mature egg is released from one of the ovaries. Some women may have some slight discomfort during ovulation usually described as a twinge or cramp or 'mittelschmerz' (German for 'pain in the middle')in the lower abdomen or back. Many women have no sensation that they are ovulating. Once released the egg travels into the fallopian tube and it lives 12-24 hours in the fallopian tube after it has been released from the ovaries. If it's not fertilized by a sperm the egg disintegrates. Sperms can survive for up to five days inside a woman's reproductive system. The 4-5 days before, and the day of ovulation are a woman's "fertile period" - the time when if she makes love she can become pregnant. Because the lengths of menstrual cycles vary, many women ovulate earlier or later than day 14 of the cycle. Stress and other things can sometimes cause a cycle to be shorter or longer.
4. The Postovulatory Phase
   Most months the egg cell simply dies in the postovulatory phase (after the egg cell is released), the endometrium continues to develop and the uterine glands secrete nutrient materials. If the egg cell meets a sperm cell, and that usually happens in the far part of tha fallopian tube, the fertilized egg continues to travel towrds the inside of the uterus. That journey takes on average about a week. Once the fertilized egg reaches the inside of the uterus it attaches itself to the uterine lining, a process called 'implantation'. Most women do not feel when implantation happens. If a woman becomes pregnant, the implanted embryo sends out signals to the woman's brain, and her menstrual period cycle will stop.If there is no implantation, hormones drop, the uterine lining can no longer be maintained and the lining of the uterus breaks down, menstrual bleeding begins, and the cycle repeats.

The First Day of the Menstrual Cycle: Cycle Day 1
The most obvious sign and the beginning of your monthly cycle is your menses or menstrual period. That's when you start bleeding. So we'll start there. Your menstrual period begins on the first day you see bright red blood (brown spotting does not count). The first day of your bleeding also happens to be the beginning of your menstrual cycle, or 'Cycle Day 1' (CD 1). So CD 1, or the first day of your menstrual bleeding or the beginning of your cycle, are all on the same day. You begin counting your menstrual cycle on cycle day 1.

Your menstrual cycle finishes on the day before the first day of your next cycle. You cannot find out how long your cycle lasts until your next regular menstrual period or bleeding begins. Menstrual cycles last on average 28 days. Pay attention to the word 'average,' it does not mean that your cycles always last 28 days, nor does it mean that they normall last 28 days. Your cycles can be different from one woman to the other.  Normal cycles may last between 21 and 35 days.

Regular cycles do not vary by more than 2-3 days each month. If your menstrual cycle changes by more than two or three days, then it's considered irregular. So 28 days in one cycle and 23 days in the next are a five-day difference, and the cycle is considered irregular.

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