Understanding the menstrual cycle
The menstrual cycle is more than just a period; it is a complex pattern of changes within the ovaries and uterus for the purpose of preparing the body for a possible pregnancy. This is regulated by the complex interaction of hormones including luteinising hormone (LH), follicle-stimulating hormone (FSH), estrogen and progesterone.
What’s normal?
- Cycle length: Between 21-35 days
The length of a menstrual cycle is measured from the first day of a menstrual period (i.e., the first day of bleeding) until the start date of the next period. Keep in mind, that every athlete’s experience of the menstrual cycle may be different and the length of your cycle length may change slightly between cycles and with age.
- Menstrual bleeding length: 3-7 days
- Menstrual bleeding amount: ~50mL of blood (2-3 tablespoons) in total (i.e., no flooding of pads and changing of pads or tampons every hour)
The menstrual cycle can be divided into two main cycles, the ovarian and uterine, each having three phases.
The ovarian cycle
The ovarian cycle consists of the follicular phase, ovulation, and luteal phase.
Follicular phase
The follicular phase involves the maturation of the ovarian follicles and preparation for the release of an egg. During the first few days of the cycle, a number of follicles are stimulated due to a rise in follicle-stimulating hormone (FSH). This occurs between day one and day 12 of the average 28 day cycle.
What to expect during this phase
Low estrogen, low progesterone
- Menstrual bleeding
- Fatigue
- Light period cramps that do not impact your day
Ovulation
High estrogen, low progesterone
Ovulation involves the release of a mature egg from the follicle. This occurs as the developing follicle causes a rise in estrogen which prompts the anterior pituitary gland to produce a surge of luteinising hormone (LH). This triggers the release of a mature egg. This stage occurs between day 12 and day 15 of an average 28 day cycle.
If sperm are present in the fallopian tube at the time of ovulation, the egg may be fertilised and commence the process of embryo development. This may result in pregnancy if the developing embryo reaches the uterus and implants into the endometrium. If the egg is not fertilised within 12 to 24 hours of ovulation, it will dissolve and be absorbed in the fallopian tube.
What to expect during this phase
- You might experience twinges of pain (sign of ovulation)
Luteal phase
During the luteal phase the follicle in the ovary that produced the egg becomes the corpus luteum. The corpus luteum produces the hormones progesterone and estrogen to provide nutrition to the endometrium, the lining of the uterus.
If an embryo has successfully implanted into the endometrium, human chorionic gonadotropin (hCG) is produced. The production of hCG causes the ovary to continue producing progesterone which is necessary to support the pregnancy. Alternatively, if there is no fertilisation or implantation, the ovary ceases producing progesterone resulting in the uterine lining shedding and the start of a period.
This phase starts after ovulation around day 15 and corresponds with the secretory phase of the uterine cycle.
What to expect during this phase
High estrogen, high progesterone
Most people also experience symptoms in the days leading to their menstrual period which are referred to as premenstrual syndrome (PMS) symptoms. This can vary between people and each menstrual cycle with common symptoms experienced include, but are not limited to:
- Headaches
- Abdominal bloating
- Mood changes
- Food cravings
- Breast tenderness, swelling and/or pain
- Skin changes
- Changes in sexual desire
- Changes in sleep
To learn more, visit our Premenstrual Syndrome (PMS) page.
The uterine cycle
The uterine cycle also consists of three phases: menstruation, proliferative phase, and secretory phase.
Menstruation
The start of the uterine cycle is menstruation or the period. Common symptoms such as cramping, nausea, breast tenderness and irritability may be experienced before or during a period. These symptoms are commonly known as premenstrual syndrome (PMS).
Proliferative phase
During the proliferative phase hormones cause the endometrial lining to grow or proliferate. Oestradiol is also released as the ovarian follicles start to mature, causing the formation of a new layer of the endometrium.
Secretory phase
The final phase of the uterine cycle, the secretory phase, corresponds with the luteal phase of the ovarian cycle. During this phase, the follicle that released the egg (corpus luteum) produces the hormone progesterone. This allows the endometrium to be receptive to the implantation of the developing embryo and support early pregnancy.
When should I seek the help of a doctor?
We recommend you seek the advice of a doctor if you experience any of the following:
- Significant changes in the pattern of your period
- The absence of a period
- Heavy bleeding (e.g., flooding of pads, changing pad/tampon every hour etc.)
- Large clots present during your period
- Severe pain that impacts on your daily activities
- Vomiting or nausea
- Blood in urine or bowel motion
- Urinary incontinence
If you have concerns about your menstrual cycle, we encourage you to get in touch with us. We have a network of specialised General Practitioners, gynaecologists and fertility specialists across Australia who will be more than happy to speak with you and discuss your individual circumstances.
With over 50 dedicated specialists across 70 consulting locations throughout the country, our friendly staff can help you choose the right medical professional to guide you and help you achieve your sporting goals. Contact us now.
