What is Ovulation?
Ovulation is the release of a single, mature egg from the ovarian follicle. The human ovary produces a multitude of ova during the course of a month, largest of which is expelled into the pelvic cavity and swept into the Fallopian tube. Ovulation does not follow a regular pattern between ovaries each cycle and which ovary releases the egg is fairly arbitrary. Once released, the egg is capable of being fertilized for 12 to 24 hours before it begins to disintegrate. If the released ovum or egg is fertilized and successfully implants, it results in pregnancy.
If the egg is not fertilized, it is passed from the reproductive tract during menstrual bleeding, which starts about two weeks after ovulation. Occasionally, cycles occur in which an egg is not released; these are called anovulatory cycles. Note that you can get your period even though you are not ovulating. Your ability to ovulate can vary from month to month.
Ovulation – The Hormones
During ovulation, two ovarian hormones, estradiol and progesterone, are produced, which create conditions conducive to fertilization.
- Estradiol is produced alone by the developing follicle before ovulation; it stimulates the glands of the cervix to secrete a particular type of mucus (“mucus with fertile characteristics”) which is essential for the sperm to pass through the cervix and reach the ovum. oestradiol also stimulates growth of the endometrium lining the uterus (womb).
- After ovulation, progesterone and estradiol are produced by the corpus luteum which forms from the ruptured follicle. This progesterone causes the abrupt change in the mucus which occurs immediately after ovulation and defines the Peak symptom. Progesterone also prepares the oestrogen-primed endometrium for implantation of the fertilized ovum.
In the absence of pregnancy, production of estradiol and progesterone begins to decline approximately 7 days after ovulation and this results in shedding of the endometrium as menstrual bleeding 11-16 days after ovulation.
Ovulation and Getting Pregnant
Ovulation is the ideal period of your cycle when your chances of getting pregnant are highest. Your fertile period starts about 4-5 days before ovulation, and ends about 24-48 hours after it. This is because sperm can live in your body for approximately 4 to 5 days, and the egg can live for 24 to 48 hours after being released. In normally fertile couples there is a 25 percent chance of getting pregnant each cycle, meaning around 75 to 85 percent of women who have sex without using birth control will get pregnant within one year. You can boost your chances of getting pregnant by learning exactly when you ovulate by understanding the cyclic hormonal and physical changes that take place in your body each month.