The term in vitro fertilization (IVF) literally means “fertilization outside of the body”. IVF is now routinely used to treat infertility caused by moderate to severe low sperm count, tubal disease and unexplained infertility.
In the IVF process, the female receives the follicle stimulating hormone (FSH) (see fertility medications) by injection. FSH stimulates the recruitment and development of multiple eggs within the ovary. Egg maturity is monitored by the rise in serum estrogen levels, and by measuring follicular growth. FSH is administered until the eggs are mature, and then human chorionic gonadotropin (hCG) is administered 36 hours prior to egg retrieval.
The eggs are retrieved transvaginally (through the vagina) using a needle guided by ultrasound. The male provides a semen sample. This specimen is specially washed and prepared to inseminate the egg. The sperm is then layered on the eggs, and one sperm attaches to and penetrate the egg’s membrane (zona pellucida) resulting in fertilization. The fertilized eggs develop into embryos.
The embryos are placed in an incubator and allowed to divide from 3 to 5 days. Where possible, 5 day old embryos (blastocysts) are transferred to the mothers uterus. Attachment to the uterus results in a developing pregnancy.