Updated: Feb 6, 2021
The Four Phases of the Menstrual Cycle
Last week I explained why I wanted to started this series, this week I want to write about the four phases of the menstrual cycle. Each phase is characterised by a natural ebb and flow of hormones, namely estrogen, progesterone and testosterone. There are many other hormones at play but I’ll save that for another post. The purpose of our cycle is to prepare the body for pregnancy.
As we move through the four phases of our cycle we may notice physical and emotional changes. Understanding your cycle and the change in hormone levels can help prepare you to live in harmony with your body making for healthy, happier periods.
Phase one - Menstruation
Many people believe that your period marks the end of your cycle, when in fact, day one of your period is day one of your cycle. Periods typically last from 3-7 days. When I had the copper IUD my periods would last at least 7 days and they were extremely heavy and painful. So far I have only had one period post coil and the bleed only lasted for 4 days which is a massive difference! Just before your period arrives progesterone levels drop, this is what leads to the break down of the uterine lining. At this point your estrogen and progesterone levels are at their lowest levels for your whole cycle. As your period arrives you may feel a sense of relief, like a weight has been lifted and a feeling of ease settles in. During your period it is likely that you will be slightly withdrawn and tired. This should be honoured, this is a time for self care, think long baths and yin yoga. During your period your cervix moves down and sits lower, it’ll feel firm and open to allow the uterine lining to exit the body. Knowing the position of your cervix is important if you want to use the natural family planning method, along with your cervical fluid. During the first couple of days of your period your body is already preparing for release of the next egg. Your body is already choosing a handful of ovarian follicles which contain a single egg. By the end of your bleed the next egg is already chosen for this cycle. After your period your cervix becomes firmer and closed. If you track your BBT (Basal Body Temperature) your period tends to arrive as your temperature drops.
Phase Two - The Follicular Phase
At the start of this phase your cervical fluid is likely to be sticky and thick. During the second stage of your cycle the ovaries continue to prepare for ovulation. Testosterone levels increase, estrogen prepares the uterus for pregnancy by thickening the lining. As we move closer to ovulation the cervix moves higher and will start to open, cervical fluid becomes creamier. Your mood and energy will be elevated so this is a good time for more cardio based workouts and executing plans. As you move towards the later stages in the follicular phase your cervical fluid will become more watery indicating that ovulation is close. If you are not looking to become pregnant extra precautions need to be taken. During this time your BBT will remain fairly constant, between 36.11℃ and 36.39℃. The temperature shifts are very minor and if you do want to track BBT you need to measure to two decimal places.
Phase Three - Ovulation
Ovulation is the shortest phase of the cycle but the phase that packs the biggest punch. Estradiol levels rise telling the hypothalamus (a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland) to trigger a mid cycle luteinising hormone (the main hormones that control the reproductive system) which initialises ovulation. Ovulation only lasts around 24-48 hours. The delicate dance between your hormones results in the egg being released from the follicle where it makes its way down the
fallopian tube towards the uterus. The emptied egg sac becomes a "gland" called the corpus luteum, the corpus luteum rapidly develops for 24 hours and then produces progesterone throughout the duration of the luteal phase. Once the egg has been released it only survives for 12-24 hours. The egg will either be fertilised or it will disintegrate. During ovulation your cervix will be at its highest point and very open. Cervical music becomes stretchy like the white of an egg, this allows and aids the sperm to reach the egg. You can tell when ovulation has happened retrospectively due to a temperature shift. After ovulation has taken place your BBT will rise to around 36.4℃ - 37℃. There is no rule as to which ovary will release the egg each cycle although research indicates that ovulation from the right ovary is more likely to result in pregnancy (1)
Phase Four - Luteal Phase
The luteal phase lasts around 11-17 days. My luteal phase is short and only around 9 days. Part of my goals for 2021 is to have healthier periods so I am interested to keep tracking my cycle to see if my lifestyle changes can increase the days I spend during this phase. The length of the follicular phase is determined by how well the follicle that released the egg can maintain progesterone production. Progesterone remains high during this phase and estrogen will start to decline. Progesterone causes a thermogenic effect on the body raising your BBT. Cervical fluid becomes stickier. You may find that your energy levels are high during this phase, your sex drive may also increase due to one last rise of estrogen as your body tries one more time to prepare for pregnancy. If the egg was fertilised then your body will prepare for growing a small human! If the egg was not fertilised then your body will prepare for phase one and your period will arrive.
Tracking Your Cycle
If you don’t already, I highly recommend tracking your cycle. There are many apps available that make it super simple. I track my BBT, cervical fluid, cervical position and energy levels. This way I can be prepared for my next cycle and plan my workouts etc around my cycle. During my period I know the last thing I want to do is HIIT training. Tracking my cycle has also made me realise how irregular my cycle is and this has motivated me to make adjustments to my lifestyle and diet so that I can have a healthier happy cycle each month. As we move through this series I will be sharing things we can all do to support our hormones and live in harmony with our cycles.
Next week I'll be talking all about cycle tracking and what we can learn from doing so. Make you you subscribe so you don't miss any posts.