Women’s Health – Sex Hormones & the Reproductive Cycle

Women’s fertility is cyclic in nature and goes through constant change.  These changes occur, not only through the transition from childhood to menopause, but on a monthly and, indeed, daily, basis.  Hormones mediate these cyclical changes and balanced hormones are essential for female reproductive health.

After the onset of menstruation, the reproductive system takes 6-8 years to develop fully at around age 20. The implications here are that for girls put on the oral contraceptive pill (OCP) at a young age (for example due to heavy periods or dysmenorrhoea), proper signalling and feedback mechanisms may never fully develop, leaving them with a potential lifetime of hormone disturbances and menstrual difficulties.

The ‘menstrual cycle’ is the term used to describe the natural hormonal and physical changes that occur in order to prepare healthy eggs (ova) within the ovaries, and develop the lining of a woman’s uterus in preparation for pregnancy. 

The menstrual cycle is divided into three phases.

The Follicular Phase  – starts at day 1 (the first day of the period) and goes to day 14 (ovulation).  During this phase the follicles (sacs which contain an egg) develop in an oestrogen dominant environment, until the dominant follicle matures and the egg is released at around day 14. 

The oestrogen dominance in the follicular phase stimulates the lining of the uterus, the endometrium, to proliferate and become more vascular, thickening in preparation for possible embryo implantation. 

Ovulation occurs once the dominant follicle has reached maturity in the ovary, following which time the egg is released and enters the fallopian tube ready to travel to the uterus.

After ovulation, the follicle from which the egg was released changes state and becomes a progesterone-secreting gland: the corpus luteum. 

The Luteal Phase is the final stage of your cycle during which time the uterus lining becomes thicker in preparation for a fertilised egg.  Progesterone is produced in the corpus luteum in increasing quantities during the luteal phase, preparing the uterine environment for fertilisation and embryo implantation.  The progesterone release after ovulation also heats the body causing a rise in temperature of between 0.1 – 0.5oC.  A sustained temperature rise after day 14 confirms ovulation.

Finally, the corpus luteum survives for about 12–16 days, and if the egg is not fertilised, the egg dies and the corpus luteum breaks down.  When the corpus luteum breaks down, the drop in progesterone causes the endometrium to break down and shed as the menstruation.  It is important to note however that women can have a “period” without ovulating.   This phase occurs from days 16 – 28.  The cycle then begins again. 

The average menstrual cycle or a healthy menstrual cycle length should be 291/4 days in length; the same as the lunar cycle.  Long or short cycles are due to variations in the length of the follicular phase or luteal phase.

With the cyclical changes there is a change in the quality and quantity of the cervical mucus.  With the increase in oestrogen in the follicular phase, the mucus increases in quantity, becomes wetter and slipperier.  This mucus is designed to allow the sperm passage to the uterus.  Just prior to ovulation the mucus is profuse, wet and clear.  At this time, many women produce clear, stretchy mucus which resembles raw egg white.  As progesterone levels increase in the luteal phase, the mucus quantity decreases and it becomes drier, pastier and more acidic.  This, in effect, acts as both a barrier and a spermicide, as sperm cannot pass through the mucus and are immobilised in a lower pH.  These mucus changes are critical for fertility and though the mucus pattern alone won’t confirm ovulation, it can tell you the potentially fertile times in a woman’s cycle.  

Note: For more information on temperature and mucus patterns and cycle charting, please discuss this with one of our Naturopaths at Nurtura Health.  


The cyclical fluctuations in sex hormones during a woman’s monthly menstrual cycle are key to her reproductive health and the changes that occur during her menstrual cycle are mediated mostly be steroidal sex hormones (i.e. oestrogens and progesterone).  All steroid hormones are synthesised from the same precursor, cholesterol. 

Numerous organs and tissues have the capacity to synthesize steroid hormones, including the adrenals, ovaries, testes, brain, adipose tissue, skin and the placenta.  The adrenal gland is the most important steroidogenic tissue in the human body and is essential for survival.  An enzyme unique to the adrenal cortex is essential for the conversion of progesterone and 17-hydroxyprogesterone into the precursors for corticosterone and cortisol, respectively.  The importance of this will become more apparent when we look at the effects of stress on steroid hormone profiles. 


There are three primary forms of oestrogens produced in the human body: oestrone (E1), oestradiol (E2) and oestriol (E3).  These exist in different ratios and have differing potencies.  E3 is the least potent and should make up around 60-80% of our oestrogens, E2 and E1 are more potent and each should make up 10-20% of the oestrogen balance.  Increased levels of the most potent oestrogen E2 are associated with increased risk of many oestrogen-dependent pathologies (e.g. endometriosis, fibroids, breast cancer, etc), therefore ensuring the right balance of oestrogens is important for women’s health.  Interestingly, progesterone facilitates the conversion of E2 to the weaker E1, so the implications of adequate progesterone production extends to facilitating safer oestrogen metabolism.

All three forms of oestrogen are metabolised by liver enzymes.  This process converts E1 and E2 into a weaker, safer form of oestrogen.  In another chemical process an enzyme which is concentrated in local tissues like breast tissue, converts the oestrogens to a more potent oestrogen metabolite, 4-OH oestrogen.  This 4-OH oestrogen is strongly associated with breast cancer development.  A third metabolic pathway is also active where enzymes convert oestrogens to the strongly proliferative metabolite, 16-OH oestrogen.  This oestrogen metabolite is associated with increased risk of oestrogen-dependent cancer, and other oestrogen-dependent conditions, including fibroids, endometriosis, PMS and dysmenorrhoea.  

What does this mean?  It is of utmost importance to have healthy liver detoxification so the 2-OH, 4-OH and 16-OH oestrogens can go through a process of conversion and detoxification in the liver to be excreted through the bowels and urine. 

If there is impairment in these processes, highly reactive substances are produced which induce tumour formation largely through binding to DNA and causing breakages in the DNA strands.  These reactive substances are linked to the development of breast cancer and other types of human cancer.  Ensuring adequate enzyme, detoxification and anti-oxidant pathways effectively “mops up” these carcinogenic metabolites to render them safe and facilitate their excretion.

For optimal oestrogen metabolism and detoxification it is also important to have adequate levels of specific activated B group vitamins.

Assessing whether this is occurring in women can be easily achieved through functional pathology tests such as the Female Salivary Hormone Profile test and 2:16-OH Oestrogen Urinary Metabolite test.  For further details on these functional pathology tests, please contact one of our Naturopaths at Nurtura Health.


Watch this space for future posts of each condition in more detail!

Disclaimer:  The advice on this website is of a general nature only and Nurtura Health expressly disclaims all liability arising out of the improper use of the information provided.  Nurtura Health actively discourages any self-diagnosis or self-medication.  Please consult your health practitioner regarding these important health issues.  All rights reserved.