Ovarian hormones are chemical messengers produced by the ovaries, small, oval-shaped glands located on either side of the uterus. These hormones play a fundamental role in regulating various bodily functions, influencing numerous systems throughout the female body and contributing to overall health.
Major Ovarian Hormones and Their Functions
The ovaries produce three primary steroid hormones: estrogens, progesterone, and androgens. Estrogens, such as estradiol, are involved in the development and maintenance of female characteristics. They contribute to breast development and the maturation of the uterus, ovaries, and vagina during puberty. Estrogens also play a role in bone metabolism, maintaining bone density, and affecting the nervous and cardiovascular systems.
Progesterone is another significant ovarian hormone, primarily produced by the corpus luteum after ovulation. Its main function involves preparing the uterine lining for a potential pregnancy by thickening the endometrium. If conception occurs, progesterone helps maintain the pregnancy. Progesterone also contributes to the development of breast lobules and alveoli.
Androgens, including testosterone and androstenedione, are also synthesized by the ovaries, albeit in smaller quantities compared to estrogens and progesterone. While some ovarian androgens are converted into estrogens within the body, androgens contribute to general protein anabolism, stimulate the growth of pubic and axillary hair, and influence libido.
How Ovarian Hormones Change Through Life
Ovarian hormone levels undergo significant fluctuations throughout a woman’s life, from puberty through reproductive years and into menopause. During the menstrual cycle, these hormones follow a precise pattern. In the follicular phase, follicle-stimulating hormone (FSH) from the brain prompts the ovaries to produce estrogen, which causes the uterine lining to thicken in preparation for pregnancy.
Mid-cycle, a surge in luteinizing hormone (LH) triggers the release of an egg from the ovary. Following ovulation, the ruptured follicle transforms into the corpus luteum, which secretes progesterone to support the uterine lining in case of conception. If pregnancy does not occur, progesterone levels decline, leading to the shedding of the uterine lining and the start of menstruation.
During pregnancy, there are shifts in hormone levels to support the developing fetus. Human Chorionic Gonadotropin (hCG) is produced, which helps maintain the uterine lining. Both estrogen and progesterone levels surge throughout pregnancy, facilitating the growth and development of the baby.
Menopause marks a natural transition, typically occurring between the ages of 45 and 55, where the ovaries gradually stop producing eggs and their hormone output declines. This decrease in estrogen and progesterone leads to irregular menstrual cycles, which eventually cease. The period leading up to menopause, known as perimenopause, is characterized by fluctuating hormone levels and can last for several years.
When Ovarian Hormones Are Out of Balance
An imbalance in ovarian hormones can affect various bodily systems. These imbalances can manifest through a range of symptoms. Common indicators include irregular menstrual periods, which may be infrequent, very heavy, or entirely absent.
Individuals may experience mood swings, hot flashes, and night sweats when estrogen levels are lower, such as during perimenopause or menopause. Weight gain, particularly around the abdomen, can also occur. Skin changes like acne, or alterations in hair growth, such as excess facial or body hair (hirsutism) or thinning scalp hair, may also be present.
Conditions like Polycystic Ovary Syndrome (PCOS) involve the ovaries producing higher-than-normal levels of androgens, which can lead to irregular periods, acne, and excess hair growth. Such imbalances can also affect fertility. Pelvic pain may also indicate underlying issues related to hormone levels.