Gonadotropins, also known as gonadotrophins, are hormones secreted by the pituitary gland. The gonadotropin-releasing hormone or GnRH pulses stimulate the pituitary gland so that it begins the production of gonadotropins.
Gonadotropins are produced by men and women and they regulate the reproductive cycle in both cases. However, men and women do not have the same levels of gonadotropins, and of course the actions regulated are different in each case.
There are three types of gonadotropic hormones: FSH, LH, and hCG. They are all involved in women’s ovarian cycle, although each one acts in a different stage of the cycle and has a different function.
Follicle-stimulating hormone (FSH)
The FSH (follicle-stimulating hormone) is most abundant during the first half of the menstrual cycle, since it is responsible for the growth of the follicles within the ovary.
For the assisted reproductive treatments, the FSH is usually prescribed for ovulation induction treatments with the aim of increasing the growing follicles and stimulating their development.
Luteinizing hormone (LH)
The LH (luteinizing hormone) is responsible for the ovulation process in women. A spike in the amount of LH may trigger ovum releasing from the antral follicle in order to release an egg into the Fallopian tubes.
This hormone is used during ovulation induction in order to maximise the conditions given during natural ovulation.
Human chorionic gonadotropin (hCG)
hCG causes final maturation of the eggs and is a pregnancy specific hormone in every pregnant woman, since it is essential to placental development, among other functions.
hCG may also be used to detect pregnancy. In addition, it provides information on the number of weeks of gestation, since its levels vary throughout pregnancy.
The hCG hormone is administered to women undergoing assisted reproductive treatments approximately 32-36 hours before follicular puncture in order to trigger ovulation.