Estrogen - How does it Fluctuate as Women Age?

Estrogen - How does it Fluctuate as Women Age?

Estrogen fluctuates considerably as we age, that’s no secret – we know by early teens we are experiencing menstruation, and that continues on from there to pregnancy alterations of levels, and if we don’t experience that aspect then our next step is the onset of perimenopause, menopause and later post menopause levels. We assume that they don’t stay consistent otherwise we would only stay in one phase right?! Duh! But how much do they change and why?

Our Very First Period

The average age for onset of our very first period as adolescent girls is around 12.4 years old, some experience their first period earlier and some later, all of which is normal. The term for the first period is called Menarche and this is the process of a maturing Hypothalamic-Pituitary-Ovarian Axis or HPO for short, this is the signaling happening between our brain and ovaries maturing for the next phase of our female lives.

In this phase, we see the first shedding of endometrial lining when ovulation is not followed by successful fertilization and the body sheds the lining it had prepared. One important not to mention here and our friend Lara Briden would agree, that having a period does not always guarantee successful ovulation, you can in fact have a period without ovulating[1]. Most young girls don’t ovulate every cycle for the first year after the initial menstruation.

During the first half our cycle, known as the ‘Follicular Phase’ we are building what is called ‘uterine lining’, the plump lining that allows for a nice happy environment in hopes of a fertilized egg. Estrogen is the main driver here and when fertilization doesn’t occur, the estrogen levels drop and Menstruation occurs.

Estrogen During Pregnancy

As we mentioned above – Our estrogen is a busy bee and works to increase tissue of the uterine lining, in hopes of falling pregnant. If successful in this mission, estrogen continues throughout the pregnancy functioning in many ways:
  • Growth of the Uterus.
  • Maintenance of uterine lining.
  • Increases circulation to the placenta.
  • Increases the growth of breasts.
  • Development of the fetus.
  • Regulates ratios of progesterone.
Levels of estrogen dramatically increase during pregnancy by an unfathomable amount where we see it go from the usual levels during our menstrual cycle of 30-800 pg/ml (picograms per milliliter) to often over 20 000 pg/ml [2]. Which is a testament to just how amazing our bodies are when we are creating another life!

Perimenopause Paradox

During perimenopause it's hard to know what to expect, you know that you are starting to see the signs of transitioning from a normal predictable period/menstrual cycle to maybe you might get it this month maybe not, it’s a surprise! Is basically what your body is saying, sometimes they can be heavy periods as estrogen has random surges stimulated, and sometimes it can be less than what you were used to. As a general rule of thumb, this phase is often seen to be the beginning of a decline in estrogen. You start to see other symptoms of a decline in hormones [3]:
  • Hot flashes.
  • PMS that fluctuates more than normal.
  • Low sex drive.
  • Vaginal Dryness.
  • Sporadic period timing.
  • Fatigue.
  • Poor sleep.
  • Night sweats.
What’s happening here?

There are fluctuations in the Hypothalamic-Pituitary-Ovarian Axis where Oestrogen and Follicle-stimulating hormone are changing from the usual levels we have during our month to month cycle. As the transition through menopause occurs from here we see less and less estrogen produced by the ovaries. Variables are also present in the instance where estrogen and gonadotropin levels are elevated higher than usually expected in conditions surrounding obesity and insulin resistance [4].

Menopause to Post Menopause

These phases merge into each other quite mutually, menopause is defined by a woman no longer having a menstrual cycle for 12 consecutive months and the post-menopause transition is where we begin to sit for the rest of our lives from here. No cycle for at least 12 months and those perimenopausal/menopausal symptoms start to ease. However, the risk for osteoporosis greatly increases as androgens and estrogens begin to decline [5].

Estrogen Dominance

Estrogen is pivotal to our health there is no question about it but it needs to remain in balance – too little and you end up with issues and too much of it will see a cascade of negatives also; such as the formation of cancerous tissues, Thyroid dysfunction, autoimmune conditions such as lupus and MS (Multiple Sclerosis), endometriosis and gynecomastia [6].

Physical symptoms can appear before these conditions arise in most cases [7]:
  • Poor mood/teary/anxiety/depression.
  • Isolated fatty deposits on the hips, buttocks, underarms, and midsection.
  • Insomnia.
  • Infertility.
  • Fibroids/endometriosis.
  • Low libido.
  • Fatigue.
  • Gynecomastia in men.
  • Irregular periods.
  • Heavy and painful periods.

There are many factors that can contribute to excessive estrogen circulating and accumulating in the body, if you feel that you identify with the symptom picture outline mentioned above it may be a good idea to contemplate booking in with a health professional for testing and next steps.


  1. Petry CJ, Ong KK, Hughes IA, Acerini CL, Dunger DB. Age at Menarche and Blood Pressure in Pregnancy. Pregnancy Hypertens. 2019 Jan;15:134-140.
  4. Stachenfeld N. S. (2014). Hormonal changes during menopause and the impact on fluid regulation. Reproductive sciences (Thousand Oaks, Calif.)21(5), 555–561.
  6. Patel, S., Homaei, A., Raju, A. B., & Meher, B. R. (2018). Estrogen: The necessary evil for human health, and ways to tame it. Biomedicine & Pharmacotherapy, 102, 403–411.doi:10.1016/j.biopha.2018.03.078