- The uterine lining is thickened to prepare for a fertilized egg and if conception does not happen, the uterine lining sheds during a menstrual period.
- A menstrual cycle is measured from the first day of a menstrual period until the first day of the next period. An average menstrual cycle is between 28 to 32 days, but shorter or longer cycles can occur.
- Ovulation usually happens between Day 11 to Day 21 of a cycle, counting from the first day of the last period.
- Those who have shorter menstrual cycles tend to be more likely to ovulate closer to day 11.
- Those with menstrual cycles on the longer side can ovulate occur closer to day 21.
- Ovulation is not always the same day each month. It can occur any time during days 11 to 21 of a menstrual cycle, and usually lasts one day.
What Are Signs of Ovulation?
Signs and symptoms of ovulation may include:
- Pain or a dull ache felt on one side of the abdomen when ovulation occurs (sometimes called mittelschmerz, which is German for ‘middle pain’)
- Change in cervical fluid, which may become thinner and more clear
- Sustained basal body temperature increase
- Breast tenderness
- Light spotting
- Abdominal bloating
- Change in cervical position and firmness
- Increased sex drive
- Heightened sense of vision, smell, or taste
- Elevated levels of luteinizing hormone, as detected on an ovulation test
People who are trying to become pregnant use ovulation prediction to determine the optimal time to have intercourse, particularly if they are having difficulty conceiving because fertility is greatest in the window in which ovulation occurs.
Methods of ovulation prediction include:
- Ovulation calendars
- Tracking periods
- Period tracking apps
- Observing cervical fluid
- Taking daily basal body temperature
What Are the Phases of a Menstrual Cycle?
A menstrual cycle is counted from the first day of menstruation to the first day of the next. An average menstrual cycle is between 28 to 32 days, but shorter or longer cycles can occur.
The four main phases of the menstrual cycle include:
- Passage of the thickened lining of the uterus (endometrium) through the vagina
- Menstrual fluid contains blood and cells from the lining of the uterus
- A menstrual period lasts on average between three days to one week
- Follicular phase
- Begins on the first day of menstruation and ends with ovulation
- The pituitary gland releases follicle stimulating hormone (FSH) to stimulate the ovaries to produce between five to 20 follicles that bead on the surface
- Each follicle contains an immature egg and usually one follicle matures into an egg and the others die
- This tends to occur around day 10 of a 28-day cycle
- The growth of the follicles stimulates the lining of the uterus to thicken in preparation for potential pregnancy
- This is the most fertile window during a menstrual cycle
- The release of a mature egg from the surface of the ovary
- This occurs mid-cycle, about two weeks before menstruation starts
- During the follicular phase, estrogen levels rise and gonadotrophin-releasing hormone (GnRH) is released, which stimulates the pituitary gland to produce increased levels of luteinizing hormone (LH) and FSH
- Higher levels of LH trigger ovulation within two days and the egg travels into the Fallopian tube toward the uterus
- An egg usually only lives about one day and if it is not fertilized by a sperm in that time, it will die
- Luteal phase
- During ovulation, an egg bursts from its follicle, but the ruptured follicle stays on the surface of the ovary and transforms into a structure called the corpus luteum that releases progesterone and small amounts of estrogen
- These hormones maintain the thickened lining of the uterus, waiting for a fertilized egg to stick
- If a fertilized egg implants, hormones are released to maintain the thickened lining of the uterus
- If pregnancy does not occur, the lining of the uterus sheds during menstruation and then the cycle repeats
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