THE MENSTRUAL CYCLE AND OVULATION PREDICTION

THE MENSTRUAL CYCLE AND OVULATION PREDICTION

Menstruation - having periods - is part of the female reproductive cycle that starts when girls become sexually mature at the time of puberty. During a menstrual period, a woman bleeds from her uterus (womb) via the vagina. This lasts anything from three to seven days. Each period commences approximately every 28 days if the woman does not become pregnant during a given cycle.

The menstrual cycle is regulated by hormones. Luteinizing hormone and follicle-stimulating hormone (FSH), which are produced by the pituitary gland, promote ovulation and stimulate the ovaries to produce estrogen and progesterone.

The menstrual cycle is divided into two parts: pre-ovulation (is called the follicular phase) and pos-ovulation (from ovulation to menstruation, is called the luteal phase). The ovarian cycle refers to the cyclical development and expelling of the egg from the ovary. Though the length and regularity of a menstrual cycle may differ, the average duration of a complete menstrual cycle is 28 days (though healthy cycles can run from 21-36 days). [See Image]
The reproductive cycle can be divided into an ovarian cycle and a uterine cycle is shown in table below.


Can you feel ovulation? [Dr Philip Owen, Dr Jeni Worden, 2005]

Ovulation usually takes place roughly 14 days after the first day of the start of a period; however, the exact timing can vary greatly from woman to woman. Some women know when they are ovulating because they can feel a slight pain in their lower abdomen. Other women may bleed slightly in the middle of their cycle.

Vaginal discharge also changes at ovulation. It increases in amount and becomes more watery due to hormonal changes. This is one of the ways that women who wish to practice natural family planning (NFP) using the mucus test can find out whether it is safe to have sex or not.

Women who do not experience such symptoms during ovulation can find out when they are ovulating by taking their temperature. This will rise by 0.5 degrees Celsius when ovulation occurs. To measure temperature effectively, it must be taken at the same time every morning before getting out of bed.

Temperature readings taken from different parts of the body such as the mouth, under the arm, in the ear or in the rectum will all give a slightly different measurement. For this reason, it is important to choose one location and stick to it. When checking for temperature, rises can occur for a variety of reasons and, therefore, should not be used as the only method of detecting ovulation.

Important facts to know about ovulation [Ollendorff A T, 2008] :

1. An egg (ovum) lives 12-24 hours after leaving the ovary
2. Normally only one egg is released each time of ovulation
3. Ovulation can be affected by stress, illness or disruption of normal routines
4. Some women may experience some light blood spotting during ovulation
5. Implantation of a fertilized egg normally takes place 6-12 days after ovulation
6. Each women is born with millions of immature eggs that are awaiting ovulation to begin
7. A menstrual period can occur even if ovulation has not occurred
8. Ovulation can occur even if a menstrual period has not occurred
9. Some women can feel a bit of pain or aching, near the ovaries during ovulation. This is called "mittleschmerz"
10. If an egg is not fertilized, it disintegrates and is absorbed into the uterine lining
11. Sperm can live in a woman's body up to 5 days after intercourse, though more often 2 days.
12. Pregnancy is most likely if intercourse occurs anywhere from 3 days before ovulation until 2-3 days after ovulation.

When are you the most fertile?
A woman's monthly cycle is measured from the first day of her menstrual period until the first day of her next period. On average, a woman's cycle normally is between 28-32 days, but some women may have much shorter cycles or much longer ones. Ovulation can be calculated by starting with the day the last menstrual period (LMP) starts or by calculating 12-16 days from the next expected period. Most women ovulate anywhere between Day 11 - Day 21 of their cycle, counting from the first day of the LMP. This is what many refer to as the "fertile time" of a woman's cycle, because sexual intercourse during this time increases the chance of pregnancy. Ovulation can occur at various times during a cycle, and may occur on a different day each month.