Estrogen

Estrogen is the major female hormone. It is primarily produced by the ovaries and small amounts are produced in the adrenal glands and fat cells. During pregnancy, the placenta also makes estrogen.

Estrogen promotes the development and maintenance of female characteristics in the human body, including breasts, pubic and armpit hair, and the regulation of the menstrual cycle and reproductive system.

Estrogen also plays a big role in reproductive and sexual development, including puberty, menstruation, pregnancy, and menopause.

Progesterone

Progesterone is produced by the ovaries after ovulation. During pregnancy, the placenta also produces progesterone.

Progesterone is responsible for:

• Preparing the lining of the uterus for a fertilized egg
• Supporting pregnancy
• Suppressing estrogen production after ovulation

Testosterone

Testosterone is produced by the adrenal glands and ovaries. This hormone is produced in small amounts and is responsible for 

• Sexual desire
• Regulation of the menstrual cycle
• Bone and muscle strength

Normal Levels of Female Sex Hormones

Estrogen levels can be determined by a blood test. Normal ranges are measured in picograms per milliliter (pg/mL):

• Adult female, premenopausal: 15-350 pg/mL
• Adult female, postmenopausal: <10 pg/mL

Levels may vary greatly throughout the menstrual cycle.

Progesterone levels can be determined by a blood test. Normal ranges are measured in nanograms per milliliter (ng/mL):

• Before puberty: 0.1-0.3 ng/mL
• During the first (follicular ) stage of the menstrual cycle: 0.1-0.7 ng/mL
• While ovulating (luteal stage of cycle): 2-25 ng/mL
• First trimester of pregnancy: 10-44 ng/mL
• Second trimester: 19.5-82.5 ng/mL
• Third trimester: 65-290 ng/mL

Testosterone levels are also determined by a blood test. Normal ranges for females is 15 to 70 nanograms per deciliter (ng/dL).

Hormones Change Over Time

It is quite normal for your hormones to change as you leave childhood and enter puberty, as you become pregnant, give birth, and breastfeed, and as you near menopause. This is natural and expected.

Puberty: During puberty, the production of your female sex hormones increases, especially estrogen, which results in

• Breast development
• Growth of pubic and armpit hair
• Growth spurt
• Increase in body fat in the hips and thighs
• Maturation of the ovaries, uterus, and vagina
• Start of the menstrual cycle

Most females enter puberty between the ages of 8 and 13.

Menstruation: Most females get their first period between the ages of 10 and 16. The menstrual cycle lasts around 25 to 36 days, and bleeding lasts between 3 and 7 days. 

Pregnancy: As conception takes place, you start to produce human chorionic gonadotropin hormone (hCG)–the hormone that shows up in your urine and is used to test for pregnancy. During pregnancy, estrogen and progesterone levels increase, preventing menstruation and helping to sustain the pregnancy.

Childbirth and Breastfeeding: After childbirth, your hormone levels start to fall immediately, returning to your pre-pregnancy levels. Breastfeeding lowers estrogen levels and can prevent ovulation, but not always, so you’ll need birth control to prevent another pregnancy.

Perimenopause and Menopause: During perimenopause, hormone production in your ovaries slows down–estrogen levels start to fluctuate and progesterone levels start a steady decline. As you near menopause, your vagina may become less lubricated, you may experience a decrease in your libido (sexual desire), and your menstrual cycle becomes irregular.

You’ve reached menopause when you have gone 12 months without a period. Menopause usually occurs around age 50. Estrogen and progesterone levels remain steady at low levels.

Hormonal Imbalance

While it is normal for hormones to fluctuate throughout the various stages of a woman’s life–puberty, pregnancy, breastfeeding, perimenopause, and menopause–a hormone imbalance can be a sign of something more serious.