In the average cycle, day 1 is the first day of your period. The follicular phase—when your ovaries are getting ready to release an egg—lasts from day 1 until day Ovulation occurs on day 14, and marks the transition to the luteal phase.
But an average-length menstrual cycle can conceal abnormal length follicular and luteal phases. If your follicular phase is less than 10 days long in other words, if you ovulate on day 10 of your cycle or earlier , it could indicate that you released an immature egg.
Immature eggs are either unable to be fertilized, or can be fertilized and have chromosomal issues. If your body loses steam before ovulation actually occurs, you may notice multiple patches of fertile cervical mucus about two weeks apart as your estrogen and LH levels rise again. This often happens in PCOS. When: From the start of the period until ovulation. What: Signals from the brain tell the ovaries to prepare an egg that will be released.
During the period, the pituitary gland a small area at the base of the brain that makes hormones produces a hormone called follicle stimulating hormone FSH. FSH tells the ovaries to prepare an egg for ovulation release of an egg from the ovary. Throughout the menstrual cycle, there are multiple follicles fluid filled sacs containing eggs in each ovary at different stages of development 5,6.
About halfway through the follicular phase just as the period is ending one follicle in one of the ovaries is the largest of all the follicles at about 1 cm 0. This follicle becomes the dominant follicle and is the one prepared to be released at ovulation. The dominant follicle produces estrogen as it grows 8 , which peaks just before ovulation happens 7.
For most people, the follicular phase lasts days, but this can vary from cycle-to-cycle 4. When: From the end of the period until ovulation. What: The uterus builds up a thick inner lining. While the ovaries are working on developing the egg-containing follicles, the uterus is responding to the estrogen produced by the follicles, rebuilding the lining that was just shed during the last period.
This is called the proliferative phase because the endometrium the lining of the uterus becomes thicker. The endometrium is thinnest during the period, and thickens throughout this phase until ovulation occurs 9. The uterus does this to create a place where a potential fertilized egg can implant and grow When: About midway through the cycle, but this can change cycle-to-cycle.
Ovulation divides the two phases of the ovarian cycle the follicular phase and the luteal phase. What: An egg is released from the ovary into the fallopian tube. The dominant follicle in the ovary produces more and more estrogen as it grows larger. The dominant follicle reaches about 2 cm 0. When estrogen levels are high enough, they signal to the brain causing a dramatic increase in luteinizing hormone LH This spike is what causes ovulation release of the egg from the ovary to occur.
Ovulation usually happens about days before the start of the next period When: From ovulation until the start of the next period. What: The sac that contained the egg produces estrogen and progesterone. Once ovulation occurs, the follicle that contained the egg transforms into something called a corpus luteum and begins to produce progesterone as well as estrogen 10, Progesterone levels peak about halfway through this phase The hormonal changes of the luteal phase are associated with common premenstrual symptoms that many people experience, such as mood changes, headaches, acne, bloating, and breast tenderness.
If an egg is fertilized, progesterone from the corpus luteum supports the early pregnancy This occurs when estrogen and progesterone hormone levels decrease and there is no pregnancy. This phase accounts for the first half of the menstrual cycle; beginning on the first day of your period and continues for 10 to 17 days. At birth, your ovaries contain all the immature eggs you will use during your entire lifespan.
Under the control of various hormones following puberty, your brain will send a hormonal signal to the Follicle Stimulating Hormone FSH to your ovaries to recruit several follicles to mature each month. We can think of this as a race amongst the follicles as to which follicle will result in a mature egg to be released at the time of ovulation.
Each follicle recruited during a cycle contains a single egg. The fastest, healthiest follicle and egg also known as the dominate follicle will win the race and release an egg ovum at the time of ovulation.
The other follicles and eggs that were in the race are then reabsorbed, having lost their chance to fully mature or ever be released. As follicles within the ovary race to mature, changes are also occurring within the lining of your uterus. Increasing amounts of estrogen stimulate a thickening of the lining of the uterus, known as the endometrium. Estrogen is the fertilizer. Other hormones are released near the end of the Follicular phase including testosterone.
These hormonal changes are responsible for increased vaginal lubrication and an increase in libido or sexual desire. Everything that took place during the Follicular phase has prepared your body for a spectacular series of hormonal events that lead to ovulation. Ovulation occurs mid-cycle in response to a series of hormonal changes that are set off by a peak in estrogen, occurring any day from day 10 to 17 of the Follicular phase. This peak in estrogen triggers a brief surge in Luteinizing Hormone LH , which triggers ovulation within usually 24 hours and occasionally up to 48 hours.
Ovulation is the time when an egg is released from the dominant follicle winner of the race within an ovary, into the fallopian tube where it can become fertilized by sperm. This is the only time during the menstrual cycle that a woman can become pregnant.
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