- Ovarian reserve: A newborn baby girl has between 1 and 2 million oocytes in her ovaries. The number of oocytes gradually decreases during her lifetime, and by the time she reaches puberty, this number has already decreased to 300,000 to 400,000 oocytes.
- Oocyte reproductive dynamics: During the reproductive years of a woman’s life a total of about 450 oocytes will be released, with one mature oocyte released at each ovulation that occurs approximately 14 days before the expected start of the next period.
- Menstrual cycles: The average menstrual cycle lasts about 28 days, but cycle length can vary from woman to woman and can be affected by factors such as stress, travel and health.
- Lifespan of oocytes: Immediately after ovulation, the lifespan of an oocyte is limited between 12 and 24 hours. To increase the chances of conception, it is best to have intercourse a day or two before ovulation.
- Site of fertilization: Oocyte fertilization by a sperm usually takes place in the fallopian tube and not in the uterus. The fertilized oocyte then travels to the uterus to implant and continue its embryonic development.
- The role of cervical mucus: Near ovulation, a woman’s body produces more cervical mucus, which becomes clearer, thinner and more “slippery” to facilitate the movement of sperm into the fallopian tube and provide a better environment for fertilization.
- Female orgasm and fertility: Although female orgasm is not necessary for conception, it is believed that contractions during orgasm may help propel sperm to the cervix, potentially increasing the chance of pregnancy.
- Identical twins: Identical or homozygous twins share exactly the same genetic material and result from a fertilized oocyte that splits into two embryos. This occurs early in pregnancy and is a random event, not affected by genetic predisposition or fertility treatments.
- Inner lining of the uterus: The lining of the uterus, known as the endometrium, thickens during the menstrual cycle to prepare for possible implantation of an embryo. If pregnancy does not occur, the lining of the uterus is shed during menstruation.
- Age and fertility: Female fertility usually peaks in the late teens and early 20s and begins to gradually decline in the early 30s. After the age of 35, fertility declines significantly and more rapidly, while the risk of pregnancy complications increases especially after the age of 40.
