An Overview of Menstrual Cycle and Fertility

A woman’s best ovulation time is 12 to 16 days before her next menstrual period starts and around five to 12 days after her last period stops. Every woman is different, so it’s up to the woman to find out the best time for ovulating if she is trying to get pregnant. Some women keep up with their menstrual cycles and fertile periods by charting the menstrual periods and ovulation times.canstockphoto6045181

Optimal Fertile Days

For determining ovulation, a woman can take her longest cycle, and subtract 11 from it. This will tell you the last fertile day. If you take the shortest cycle and subtract 19 from it, this will be your first fertile day.  For example if a woman has cycles that occur every 27- 30 days then her fertile period will be day 8- 19  (30-11= 19 and 27-19 = 8) of the cycle. If you do this over the months, keep a record or chart it, you should be fertile from days 8 to 19.

Basal Body Temperature

Even though you can do this simple calculation for optimal fertile days, it is still a wide range of dates to go by. You can actually narrow down the most fertile days by charting your basal body temperature (morning temperature after you wake up). This can range from 96 to 98 degrees Fahrenheit in some women. You will notice a change of four to eight tenths of a degree temperature raise if you have ovulated within the past 24 hours or less.

Cervical Mucus Evaluation

Another way of telling if you are in your fertile period time is to pay attention to your cervical mucus. The cervical mucus is the moisture and vaginal contents that most women notice when they wipe. The mucus can range from a dry (right after their period) to a stickier texture, which means ovulation is approaching. You will also notice it being stretchy, semi-transparent, and wet once ovulation is about to occur. Once you notice the stretchy mucus, ovulation usually occurs within 96 hours.

Cycle Day-by-Day

The chart below will help you make a chart to keep up with your own ovulation and most fertile days by showing what happens on an average 28 days cycle.canstockphoto0930939

  • Days 1 to 5: Your estrogen and progesterone levels become low, and your body temperature is between 96 and 98 degrees Fahrenheit if you are not pregnant. This means the dead tissue lining in the uterus is shedding.


  • Days 6 to 7: Days 6 to 7: Gonadotropin releasing hormone (GnRH) releases from the ovaries from the hypothalamus, a brain structure which regulates ovulation andfemale hormones. The GnRH also tells the pituitary gland of the brain to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). These hormones cause the eggs in the ovaries to start growing. When the eggs begin to grow, they produce estrogen, and the progesterone level stays low. The cervical mucus is dry through the eighth and ninth day.
  • Day 8: By day eight, the lining of the uterus becomes thicker and generates a richer supply of blood vessels due to the increase of secretion of estrogen. This happens in order for the uterus to receive a fertilized egg. The FSH and LH levels will reduce during this time.


  • Day 10: Secretions become whitish or yellow-colored and the cervical mucus is wet, cloudy, and sticky by day ten.


  • Day 12: By day twelve, ovulation nears as mucus is now slippery, stretchy, and clear. This is the best time to become pregnant. Many women do not know this, but sperm will survive from two to five days after intercourse. So even though ovulation is days away, pregnancy can still occur from sex due to the survival of the sperm.


  • Day 13: Estrogen increases and LH rises rapidly.


  • Day 14: An egg is released by the ovary and the estrogen level falls fast. The egg will live from twelve to twenty-four hours. This is ovulation.


  • Day 15 (may extend to day 24): The empty egg follicle which is the corpus luteum, secretes increasing amounts of progesterone. This process helps prepare the uterus for a possible pregnancy. FSH and LH levels begin to drop.



  • Day 17: The fertile period is over when the body temperature has stayed high for three days in a row.


  • Day 18: The cervical mucus starts becoming cloudy on day eighteen.


  • Days 21 to 22: The level of progesterone peaks.


  • Day 25: The corpus luteum breaks apart, and if fertilization occurs, your progesterone level remains high. If the egg was not fertilized, progesterone begins to drop and cervical mucus is sticky.Best Denver fertility clinic


  • Day 27: Mucus becomes dry or non-existent.


  • Day 28: Estrogen level decreases, and progesterone production drops fast. Mucus becomes thicker, and if you aren’t pregnant, your menstrual cycle should begin.


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