The relationship between hormones and sex life

Female sex hormones, like estrogen and progesterone, play vital roles in sexual development, reproduction and overall health. These chemical messengers are produced in the ovaries, adrenal glands and fat cells, and increase during puberty and pregnancy.

Long-term hormonal imbalances can cause low libido. They can also be a sign of an underlying health condition or side effect from medications.

1. Estrogen

Estrogen is responsible for the development of female reproductive anatomy, including the vagina and uterus. It promotes feminine traits such as padded hips and breasts, shapes the body during puberty to look differently than a man’s, and prepares the female body — from menstruation through childbirth and beyond — to produce and nurture a baby.

Estrogens also control the lining of the uterus (endometrium). They increase its thickness and blood flow, cell types, protein content and enzyme activity; they can even change a cell’s shape.

The body makes estrogen in the ovaries, fat tissues and other organs; it is also found in men, trans-women and post-menopausal women. It binds reversibly to a protein in the blood, called sex hormone-binding globulin. Once bound, it travels to target tissues and binds to estrogen receptors on cells to affect the way genes are transcribed, or translated into proteins. During pregnancy, estrogens signal the uterus to slough off dead tissue and prepare for the birth of the baby.

2. Testosterone

Testosterone is a hormone that people assigned male at birth (AMAB) produce in their testicles and in the adrenal glands. It is an androgen, which means that it promotes the development of masculine characteristics, such as the growth of body hair. In women, the ovaries produce estrogen and small amounts of testosterone. But while researchers have long linked women’s hormones to sexual desire, levels of both estrogen and testosterone vary widely from woman to woman.

Testosterone acts as a circulating prohormone for dihydrotestosterone, which then converts to the more active androgen androstenedione in tissues that are sensitive to androgens such as the testes, prostate gland, hair follicles and muscles. In addition to promoting masculine traits, it initiates the development of the internal and external genitalia in boys during puberty, increases blood cell formation and muscle strength, and maintains sperm production and bone density in men. It also enhances libido in both men and women. It’s thought that fluctuations in testosterone in response to arousal are what prompts sexual behavior.

3. Vasopressin

A peptide hormone called vasopressin (a.k.a. antidiuretic hormone or ADH) prevents excessive urine production by increasing the reabsorption of water in the kidney. It also causes blood vessels to constrict, thereby increasing blood pressure. Thus it acts as a critical homeostatic regulator of normal serum osmolarity and hypovolemia (low blood volume).

The neuropeptide oxytocin and vasopressin are both found in the brain. They are associated with a variety of functions including social behavior, aggression and the regulation of blood pressure. Oxytocin is involved in pair bonding, while vasopressin has been associated with social recognition memory. Both oxytocin and vasopressin can induce sexual arousal.

Although direct measurements of fetal hormones are impossible due to ethical concerns, there is evidence that fetal oxytocin and vasopressin levels correlate with later-life sex drive. Women with high oxytocin and low vasopressin levels appear to have lower sex drives than those with the opposite pattern. A similar correlation is seen with progesterone.

4. Oxytocin

Oxytocin is so well-known for its role in human bonding, including mother-infant attachment and romantic love, that it’s also known as the “cuddle hormone.” It’s produced when you cuddle with a loved one or receive affection from them, and is released during sexual activity.

But oxytocin has many other roles too. For example, it can reduce agitation and depression. It’s also a major player in breastfeeding, and helps you stay calm during labor and childbirth. It’s even responsible for the nocturnal peak in uterine activity during pregnancy.

Studies suggest that oxytocin can increase the motivation to engage in sexual behaviour for females during the periovulatory phase of the menstrual cycle, when estrogens are high and progesterone is low. In addition, oxytocin is thought to play an important role in female sexual arousal and orgasm. In fact, it’s the oxytocin release that causes the sensation of closeness during climax. But more research is needed to understand how oxytocin affects female sexual motivation.