Your Life with Estrogen

Three generations of women

If you’re a woman, then you’re already pretty familiar with hormones—or at least, how they make you feel. From puberty onward, the levels of hormones such as estrogen will fluctuate along with our menstrual cycles, during pregnancy, and before, during and after menopause. But what is estrogen, really? And why do the levels rise and fall?

What is estrogen?

Estrogen is the main female sex hormone (actually, a group of similar hormones) produced mostly in the ovaries, responsible for the development and regulation of the female reproductive system and the physical characteristics that make us appear “feminine.”

Why do estrogen levels fluctuate?


During puberty, estrogen levels rise and cause many of the rapid physical changes that girls experience, including the growth of breast tissue, changes in body shape and fat distribution, growth of hair in the pubic area and underarms, and the start of menstruation.

Menstrual cycle

During the menstrual cycle, estrogen levels will fluctuate fairly predictably—rising to gear up for pregnancy, and then falling again if the egg is not fertilized to signal the body to menstruate.


When a woman does become pregnant, estrogen will work with her body to stop further ovulation, increase breast tissue, promote lactation and even help with the growth of baby’s organs and bones.

Perimenopause and menopause

As a woman moves out of her childbearing years and closer to menopause, ovulation becomes less predictable. Typically, the process slows down, and the body makes less estrogen simply because it’s not needed to support potential pregnancy any longer.

Sometimes, though, ovulation goes a bit haywire before finally settling down, leading to erratic periods and irregular hormone levels. These fluctuations cause many of the unpleasant symptoms of menopause. For example, high estrogen levels may cause:

  • Bloating
  • Breast tenderness
  • Heavy menstrual bleeding
  • Uterine fibroids

Low levels of estrogen can lead to:

  • Fatigue
  • Insomnia
  • Bone loss
  • Hot flashes
  • Night sweats
  • Headaches
  • Heart palpitations
  • Vaginal dryness
  • Mood problems, like depression
  • Difficulty concentrating

If fluctuating estrogen levels are making you uncomfortable, talk to your doctor about the benefits and risks of hormone replacement therapies, as well as other ways to manage your symptoms.