THE MENSTRUAL CYCLE
THE 4 PHASES.
The menstrual cycle is made up of 4 phases:
- Phase 1: Menstruation
- Phase 2: Follicular phase
- Phase 3: Ovulation
- Phase 4: Luteal phase
WHAT HAPPENS DURING THE PHASES?
PHASE 1: MENSTRUATION
Each cycle begins with the first day of your period.
If a fertilized egg did not implant in the previous cycle, i.e. you are not pregnant, the uterine lining that built up in the previous cycle is shed during menstruation and the female sex hormones estrogen and progesterone are at their lowest levels.
PHASE 2: FOLLICULAR PHASE
As soon as your period is over, the follicular phase comes into play.
During the follicular phase, your brain releases the so-called follicle-stimulating hormone (FSH). This stimulates the maturation of follicles (small egg "bubbles" in which eggs mature) in your ovaries. During the follicular phase, only one follicle usually develops as the dominant one and continues to grow - this is the follicle that bursts when you ovulate.
The follicles produce estrogen, which is why your estrogen level rises increasingly during the follicular phase.
PHASE 3: OVULATION
During ovulation, your estrogen levels peak, causing your brain to release the so-called luteinizing hormone (LH), which causes the follicle that has matured in the follicular phase to burst and release an egg.
The egg travels through the fallopian tubes into your uterus and is now waiting to be fertilized by a sperm. The egg is now capable of fertilization for a short period of about 24 hours, so your body prepares itself for the possibility of becoming pregnant.
PHASE 4: LUTEAL PHASE
Once ovulation ends and the luteal phase sets in, this is where the fun really starts.
After your dominant follicle has burst and released an egg, the empty follicle becomes a so-called corpus luteum. This produces the corpus luteum hormone progesterone, which plays an important role in the luteal phase. The rising progesterone level prepares your uterine mucus for the implantation of a fertilized egg.
If your egg is not fertilized, i.e. you are not pregnant, the corpus luteum dies after a few days. The estrogen and progesterone levels then drop, your period starts and a new cycle begins all over again.
By the way, there is also a second estrogen peak happening during the luteal phase - a real hormonal chaos.
