What are the 4 Phases of the Menstrual Cycle?

As we develop greater awareness of our menstrual and reproductive health, there are four different phases of the menstrual cycle to learn about. The days between your first day of bleeding and your next period are split into parts, or phases. Our sex hormones, estrogen and progesterone for example, are produced at varying rates throughout the phases and contribute to different parts of our reproductive processes. The reproductive process happens based on communication between the brain, ovaries and uterus.
 
Let’s learn what the four phases of the menstrual cycle are.

What are the 4 Phases of the Menstrual Cycle?

Menstrual Phase

Lasting on average 3-7 days, the menstrual phase begins with your first day of bleeding. If none of the eggs have been fertilized by sperm, the release of blood, mucus, and tissue signifies the shedding of the uterine lining, or endometrium.
 
Hormones Involved
Estrogen and progesterone hormone levels drop during menstrual periods. Your hormones are at their lowest point in your cycle.

Follicular Phase

The follicular phase starts with menstruation, beginning on day one of your cycle, and concluding with ovulation. On average, days 6 through 14 of your cycle are when the lining of the uterus begins to re-grow, and follicles are stimulated within the ovaries.
 
Hormones Involved
The hypothalamus, in the brain, releases a signal that triggers the pituitary gland to release follicle-stimulating hormone (FSH). FSH tells the ovaries to produce small sacs called follicles which contain immature eggs.  
 
The healthiest follicle in the ovary will mature and be released during ovulation of each cycle while the rest dissolve and are re-absorbed into the body. A maturing follicle triggers a surge of estrogen which is partly responsible for thickening the uterine lining for potential implantation. Progesterone also is a hormone that stimulates the buildup of the uterine lining for implantation. 

Ovulatory Phase

Around 14 days before menstruation occurs, the ovary releases a matured egg. This is ovulation. After the egg is released, it is viable for fertilization for 12-24 hours.
 
Hormones Involved
Rising estrogen triggers luteinizing hormone (LH) which triggers the release of the egg from the ovary. Ovulation typically lasts 12-24 hours and can be noted by an increase in basal body temperature and thicker, egg white-like discharge. You’re likely most fertile in the 2-3 days prior to ovulation or when you register the peak in basal body temperature.  
 
If you are on some forms of birth control, the incorporation of synthetic hormones serves to prevent ovulation from occurring, as well as thickens mucus to stop sperm from meeting an egg.

Luteal Phase

This is the last phase of your menstrual cycle. It typically occurs around day 15 and lasts until the day before the first day of your next bleed.  
 
During ovulation, the follicle releases the matured egg, or ovum. The ovum leaves the ovary and travels down through the fallopian tubes to the uterus. Fertilization occurs in the fallopian tubes so that once the fertilized egg, or embryo, arrives in the uterus, it can attach itself to the thickened lining, or implant itself.
 
Hormones Involved
The corpus luteum, a mass of cells, forms in the uterus after your ovaries release an egg and releases hormones, progesterone and estrogen. If fertilization occurs, producing progesterone encourages the uterine lining to thicken to support the fertilized egg, or embryo.  
 
If this implantation occurs, human chorionic gonadotropin (hCG) is produced and is the hormone picked up by a pregnancy test. It works to protect the corpus luteum and encourage the thickening of the uterine lining for confirmed implantation.   
 
At this point, if fertilization hasn’t occurred, estrogen and progesterone hormone levels drop, and menstruation occurs again. The uterus sheds its lining, containing blood, mucus, and tissues.

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Getting to know the different phases of your menstrual cycle can be useful for family planning. Being able to pinpoint roughly when ovulation occurs can improve your chances of conceiving. Becoming aware of the four phases of the menstrual cycle can also give indications of your menstrual and overall health. Tracking your period and related symptoms, like if you experience breast tenderness or cramping, can allow you to prepare for how to cope with monthly fluctuations.  

Tracking your cycle can help you draw conclusions about how you might feel during each of these phases. For example, during some phases your energy may be higher, you’ll be able to accomplish harder workouts and you’ll feel empowered. Or during the luteal phase, you might feel like curling up at home with a good book versus going out to an event. Responding to the messages you get from your body can allow you to work with instead of against your body’s natural needs and desires. By aligning your wellness practices with these phases, you can optimize your energy, support your emotional well-being, and promote overall health. Let your menstrual cycle guide you towards a healthier, more balanced lifestyle.