Sex or reproductive hormones have multiple functions in both males and females. In general, they are responsible for the development of the secondary sex characteristics during puberty. Later in life, during adulthood, they are in charge of regulating the reproductive cycle.
In females, sex hormones are releases from the ovary, regulate the menstrual cycle, and control endometrial growth. In males, the are produced in the testes and play a significant role in the sperm production process (spermatogenesis).
The different sections of this article have been assembled into the following table of contents.
Regulation of hormone production
Sex hormones are found in both males and females. However, their levels differ based on your sex. For instance, androgens are the main male hormone, while estrogen is the key female hormone.
Aside from this, the endocrine system that regulates sex hormone production in the gonads works equally in both cases. The regulation of the reproductive function start in the brain, where one can find two fundamental structures:
- Located in the basis of the brain and responsible for the production of GnRH (gonadotropin-releasing hormone) intermittently. GnRH stimulates the pituitary gland to trigger the release of other reproductive hormones as well.
- Pituitary gland
- Also called hypophysis, it releases gonadotropins due to the effect of GnRH, which is activated through the hypophyseal portal system. Gonadotropins are stimulating hormones that are present in both the ovaries and the testicles.
Gonadotropins, also known as hypophyseal hormones, are listed below:
- Follicle-stimulating hormone. It stimulates the gonads to produce gametes, that is, eggs and sperm.
- Luteinizing hormone. Also acts over the gonads, but has other functions as well.
- It is regulated differently, since it’s production depends on the dopamine secreted by the pituitary gland. It stimulates the production of milk in the mammary glands.
The pituitary gland is also responsible for the secretion of oxytocin and vasopressin (antidiuretic hormone), which have different functions in males and females.
Male sex hormones
In men, hormones that are synthesized by the pituitary gland have a direct effect on the testes in order to regulate the following main functions:
- Sperm production as a response to the effect of FSH. It takes place in the Sertoli cells, which can be found in the seminiferous tubules.
- Production of steroid hormones, such as testosterone, as a response to LH. It occurs in the Leydig cells, found in the interstitial tissue of the testicles.
Both processes are perfectly regulated by a positive-negative feedback mechanism that involves testosterone (TST), the main male sex hormone. On the one hand, TST stimulates the production of sperm. However, when TST levels in blood rise, a signal is sent to stop the secretion of LH in the brain, and subsequently the release of testosterone.
TST is a type of steroid hormone, which means that it is created from cholesterol. In addition to the regulation function already explained above, it has the following functions in males as well:
- To develop the reproductive system (penis and testes) in male fetuses
- To promote the growth of the penis, testicles and hormone secretion during puberty
- To trigger the development of the male sex characteristics: muscle mass, bone density, body hair, increase in sex drive, voice changes…
You may also enjoy some further information reading this: What Is the Function of Testosterone (TST)?
Another crucial hormone in males is inhibin (INH), which is released by the Sertoli cells. The function of INH, even though it regulates spermatogenesis as well, is the opposite of testosterone: INH levels increase as sperm are produced. Afterwards, this hormone sends signals to the brain to reduce the levels of FSH.
Female sex hormones
Sex hormone released by the ovaries are androgens, estrogen, and progestogen.
As it happens in the testicles, the regulation of steroidogenesis in females depends on FSH and LH. In this case, hormone regulation follows the following steps:
- LH triggers androgen production in the ovarian theca cells.
- Next, androgen turn into estrogens in the granulosa cells, a process that occurs thanks to the action of FSH.
- The menstrual cycle begins, and subsequently the levels of estrogens rise.
- Halfway through the menstrual cycle approximately, the so called LH surge occurs in order to cause ovulation in the woman.
- Right after ovulation, granulosa cells start synthesizing progesterone, and the follicle becomes the corpus luteum.
The production of female sex hormones is regulated by a complex feedback system that regulates the menstrual cycle as well. Want to learn more about this? Then don’t miss this guide: The Different Phases of the Menstrual Cycle.
Continue reading to get a much deeper insight about the primary female sex hormones:
Estradiol plays a major role when it comes to talking about estrogens. Even though the ovaries are the main source of estradiol production, it takes place in the suprarenal glands too.
The production of estradiol, and subsequently its levels, increase during puberty and remain consistently high during the childbearing age of women until menopause, when they start decreasing. However, it should be noted that estradiol levels vary depending on the day of the menstrual cycle.
The main functions of estradiol throughout a woman’s reproductive years include:
- To regulate the development of the female reproductive system: ovaries, womb and vagina.
- To cause the secondary sex characteristics to appear during puberty: breast development, first menstrual period, hair growth, higher-pitched voice, skeletal changes, etc.
- To make sure that a single ovarian follicle per menstrual cycle develops.
- To stimulate the production of LH in order to make ovulation possible.
- To promote endometrial growth during the first half of the menstrual cycle.
- To regulate the consistency of vaginal discharge during the fertile window.
Progesterone is a sex steroid that is key to the overall menstrual cycle, but most importantly during pregnancy.
During pregnancy, the ovaries and placenta are the organs responsible for the secretion of progesterone, although it may be released by the adrenal glands and the liver as well.
As in the case of estradiol, progesterone production starts during puberty, and starts dropping in menopausal women. Progesterone has a role in the development of the secondary sex characteristics to some extent, too.
Nonetheless, these are the most significant functions of progesterone in women:
- To promote endometrial receptivity in order to make embryo implantation possible.
- To relax the muscles of the uterus to favor embryo implantation.
- To thicken the cervical mucus in order to create the mucus plug during pregnancy.
- To stimulate the production of milk after delivery.
- To promote the start of menstrual periods monthly by decreasing its levels at the ends of each cycle.
FAQs from users
What happens if female sex hormones are low?
The two major female hormones produced from the ovary are estradiol and progesterone. While the level of progesterone can be consistent with ovulation, the level of estradiol is much less useful. In the first half of the menstrual cycle (proliferative phase) up until ovulation estradiol levels range from 40-400 pg/mL. Levels less than 40 pg/mL are consistent with ovarian suppression from medication or ovarian failure, e.g. menopause.
In the proliferative phase, progesterone levels remain less than 1.5 ng/mL. The luteal phase (follows ovulation) is dominated by the hormone progesterone and its level begins to rise at ovulation, peaks one week later, then falls if no pregnancy occurs. As a result, due to its fluctuations, a random blood progesterone level is of no value to judge a “good luteal phase”. So, any level above three ng/mL is all that is needed to presume ovulation; a higher number is meaningless and not a measure of a “good ovulation”.
What hormones cause female arousal?
Estrogen, progesterone, and testosterone are the hormones responsible for increasing sexual desire in females. However, the most influential hormone, and the one that increases libido the most, is testosterone.
Which hormone is called ‘the love hormone’?
Oxytocin is known as the love, cuddle, or bonding hormone because it plays a major role in causing contractions at childbirth and also helps lactation. Actually, it is a biochemical produced in the brain.
Is it possible to increase female sex hormones naturally?
No, it is not possible naturally. However, certain hormone drugs can influence the hormonal levels in women and help control the menstrual cycle. In this sense, we can find the following medications:
- Contraceptives: Composed of estrogen and progesterone, which act by inhibiting ovulation and preventing pregnancy.
- Gonadotropins: Used to cause ovarian stimulation in patients who undergo fertility treatment.
- Estrogen patches & progesterone pessaries: Used to prepare the endometrial lining during a replacement cycle in IVF patients.
Suggested for you
Sex hormones allow us to get a great deal of information about the fertility of both males and women. To get an overall idea of the different tests used to evaluate fertility in males, read: Male Fertility Testing – How Do You Know if a Man’s Sperm Is Fertile?
On the other hand, it is possible to evaluate female fertility by measuring the levels of the main sex hormones, too. See this for more: Female Fertility Tests – How Do You Know if You Can’t Get Pregnant?
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