What is ovulation?
Ovulation is the process by which an egg becomes mature within the ovary and is released—normally about once per menstrual cycle (once a month). Ovulation is controlled by a delicate balance of multiple hormones produced by the pituitary gland. Some of the primary hormones include follicle-stimulating hormone (FSH), which “activates” a certain number of follicles within the ovary. One of those follicles continues to develop and mature. Luteinizing hormone (LH), also from the pituitary, then increases, telling the mature egg to break free from the follicle and travel down the fallopian tube, where it may be fertilized by sperm.
During a normal menstrual cycle (period), only one or two eggs progress to maturity. In an effort to increase the chances for a pregnancy with In Vitro Fertilization (IVF) or Intrauterine Insemination (IUI), it is necessary to stimulate multiple eggs to develop. This increases the number of oocytes (eggs) available for ovulation, fertilization and implantation
In order to ovulate, you need to have enough eggs in your ovaries as per right quality for which you need to have the right balance of hormones—FSH, LH, estrogen, and progesterone—to properly control the process.
Maturity and retrieval of an oocyte (egg) is guided by the number, size and growth of follicles along with the production of Estradiol, the primary hormone produced by a healthy egg. The follicle is a small fluid-filled structure located in the ovary which contains the oocyte. The amount of fluid in the follicle increases as the egg matures, thereby increasing the size of the follicle. This growth can easily be observed and measured by ultrasound. The measurement of Estradiol and Progesterone in the blood also determine maturity of the eggs and the timing of the retrieval. This is why your blood is frequently drawn during your treatment.