Understanding Your Menstrual Cycle

March 20, 2021

A woman’s body goes through a series of phases in order to get ready for a possible pregnancy.  That series of hormonal events is referred to as the menstrual cycle.

An egg develops and gets released from the ovaries during each menstrual cycle.  There is a lining in the uterus that builds up and if a pregnancy doesn’t occur, that lining will be shed during a menstrual period. Then a new cycle will begin.

Taking a look at each phase.

  • menstrual phase
  • follicular phase
  • ovulation phase
  • luteal phase

Phases may vary for each individual in regards to length and can also change over time.

Menstrual phase

The first phase is the menstrual phase – it is also when you get your period.  It begins when an egg from the previous cycle isn’t fertilized. Because pregnancy hasn’t taken place, levels of the hormones estrogen and progesterone drop.

That thickened lining of your uterus – which generally would support a pregnancy, is no longer needed.  The lining is then shed through your vagina. During your period, a combination of blood, mucus, and tissue from your uterus is released.  The duration of the menstrual phase can last anywhere from 3 to 7 days.

Common symptoms during this phase can include:

  • cramps
  • tender breasts
  • bloating
  • mood swings
  • irritability
  • headaches
  • tiredness
  • low back pain

Follicular phase

What is known as the follicular phase starts on the first day of your period (it does overlap with the menstrual phase) and ends when you ovulate.

It begins when the hypothalamus sends a signal to your pituitary gland to release follicle-stimulating hormone (FSH). This hormone stimulates your ovaries to produce around 5 to 20 small sacs called follicles and each follicle contains an immature egg.

In most cases, only the healthiest egg will mature. In some cases, a woman may have two eggs that mature.  The rest of the follicles will be reabsorbed into your body. Those follicles that mature sets off a surge of estrogen that thickens the lining of your uterus. Which in turn creates a nutrient-rich environment for an embryo to grow.  The average length of the follicular phase is 16 days.  However, it can range anywhere from 11 to 27 days, depending on your cycle.

Ovulation phase

Rising estrogen levels during the follicular phase trigger your pituitary gland to release luteinizing hormone (LH). This is what starts the process of ovulation.  During ovulation, your ovary releases a mature egg. That egg then travels down the fallopian tube toward the uterus to be fertilized by sperm.

The ovulation phase is the only time during your menstrual cycle that you can become pregnant. There are symptoms that can help indicate when you are ovulating:

  • There is a slight rise in your basal body temperature.
  • You may see a thicker discharge that has the texture of egg whites.

Ovulation can occur around day 14 if you have a 28-day cycle or right in the middle of your menstrual cycle. It lasts about 24 hours. The egg will die or dissolve if it isn’t fertilized after a day.

Luteal phase

After the follicle releases the egg, it then changes into the corpus luteum (a mass of cells that forms in an ovary). This structure then releases hormones, which include progesterone and some estrogen. The rise in hormones keeps your uterine lining thick and ready for a fertilized egg to implant.

If you become pregnant, your body will produce human chorionic gonadotropin (hCG). Which is the hormone that pregnancy tests detect. It also helps maintain the corpus luteum and keeps the uterine lining thick.  However, if your pregnancy does not occur – the corpus luteum will shrink away and be resorbed.  This causes decreased levels of progesterone and estrogen which leads to the onset of your period.  The uterine lining will then be shed during your period. You may then experience symptoms of premenstrual syndrome.  

Symptoms of PMS can include:

  • bloating
  • breast swelling, pain, or tenderness
  • mood changes
  • headache
  • weight gain
  • changes in sexual desire
  • food cravings
  • trouble sleeping

The luteal phase can last anywhere from 11 to 17 days. 

Menstrual cycles can vary and can also change for each individual at different stages of life.  It can be helpful to track your periods.  Record when they start and end.  Note if you have spotting between periods.  If you feel as though you are experiencing an irregular cycle – monitoring your cycle can help you and your doctor identify potential causes. 

Signs that may indicate a problem with your menstrual cycle

  • You’ve skipped periods, or your periods have stopped entirely.
  • Your periods are irregular.
  • You bleed for more than seven days.
  • Your periods are less than 21 days or more than 35 days apart.
  • You bleed between periods (heavier than spotting).

Certain events and conditions can affect a person’s menstrual cycle. These may include:

  • pregnancy
  • eating disorders
  • use of hormonal birth control
  • uterine fibroids
  • polycystic ovary syndrome

At OB-GYN Women’s Centre of Lakewood Ranch, we provide a variety of services. No matter your age or medical history, we’ll help you feel comfortable and answer all of your reproductive health-related questions.

Call us today to schedule an appointment.