Fertility medication, better known as fertility drugs, are drugs which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. There are currently very few fertility medication options available for men.
The main techniques involving fertility medication in females are:
- Ovulation induction, with the aim of producing one or two ovulatory follicles for fertilization by sexual intercourse or artificial insemination
- Controlled ovarian hyperstimulation, which is generally part of in vitro fertilization, and the aim is generally to develop multiple follicles (optimally between 11 and 14 antral follicles measuring 2–8 mm in diameter), followed by transvaginal oocyte retrieval, co-incubation, followed by embryo transfer of a maximum of two embryos at a time.
- Final maturation induction of follicles, also triggering a predictable time of ovulation.
Either Gonadotropin-releasing hormone (GnRH) or any Gonadotropin-releasing hormone agonist (i.e. Lupron) may be used. GnRH stimulates the release of gonadotropins (LH and FSH) from the anterior pituitary in the body.
Clomiphene (trademarked as Clomid) is a selective estrogen receptor modulator (SERM). It is the most widely used fertility drug. It is used in ovulation induction by inhibiting the negative feedback of estrogen at the hypothalamus. As the negative feedback of estrogen is inhibited, the hypothalamus secretes GnRh which in turn stimulates the anterior pituitary to secrete LH and FSH which help in ovulation.
Although primarily a breast cancer treatment, aromatase inhibitors are also used in ovulation induction, probably through a mechanism similar to clomiphene. Aromatase inhibitors will decrease the amount of testosterone converted to estradiol. Less estradiol circulating in the body will decrease the negative feedback at the level of the hypothalamus and result in sustained FSH secretion. More FSH will be available to stimulate the ovary and mature multiple follicles for ovulation. This is a common fertility treatment to treat women with PCOS.
For example, the so-called menotropins consist of LH and FSH extracted from human urine from menopausal women. There are also recombinant variants which are created by inserting the DNA coding for it into bacteriae. The bacterial DNA is then called Recombinant DNA. Examples of recombinant FSH are Follistim and Gonal F, while Luveris is a recombinant LH.
Human chorionic gonadotropin
Human chorionic gonadotropin (hCG), also known as the “hormone of pregnancy” is a hormone that is normally produced during pregnancy and plays an integral role throughout reproduction. It is crucial in maintaining pregnancy, from the stages of placentation through to early embryo development. hCG is also used in assisted reproductive techniques as it can be used to replace Luteinizing Hormone (LH) in final maturation induction.
The use of fertility drugs is highly correlated with other ovarian cancer risk factors which complicates the direct contribution of the fertility drugs to ovarian cancer. Numerous studies indicate the risk of developing ovarian cancer as a result of fertility drugs is insignificant, but long-term exposure to fertility drugs may require further studies to determine their role in ovarian tumors and other health risks. Estrogen antagonists and gonadotropins may stimulate multiple follicles and other ovarian hormones leading to multiple birth and possible ovarian hyperstimulation syndrome.
Development of ovarian hyperstimulation syndrome (OHSS) is dependent on the administration of human chorionic gonadotropin (hCG) and is mediated through vascular endothelial growth factor (VEGF). OHSS is characterized as cystic enlargement of the ovaries. Multiple birth is especially deleterious due to compounding risks including premature delivery and low birthweight, pre-eclampisa, and increased risk of neonatal mortality. While triplet births have been declining in ART, multiple births remain over 50% of births from IVF. However, there are limitations to this date, as 4% to 8% IVF clinics to do not report their data to the CDC.
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