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Charting Your Cycle

The Science Behind Using The Fertility Awareness Method

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The Fertility Awareness Method is about becoming aware of the fertile and in-fertile phase of each menstrual cycle.

fertility awareness method of birth control

Artist: Drømsjel

How does Fertility Awareness work?

Simply explained, there are two main hormones that switch “on” in the body at separate times of the month; Estrogen for the first half and Progesterone for the second half.

Your Basal Body Temperature (BBT), Cervical Mucus (CM) and Cervix are each affected by these hormones, giving us the signs we need to practice the Fertility Awareness Method.

You can use the method’s 4 rules to decide whether you would like to try to conceive, abstain, use a barrier method to prevent pregnancy, or simply use the observed signs to follow your Gynecological health. You will not receive any negative side effects by practicing the Fertility Awareness Method.

The science

Estrogen begins to release from the ovaries on Cycle Day 1 (first day of menstruation), lowering BBT and increasing water content in CM as ovulation approaches.

CM is the deciding factor on whether sperm will be able to make it to the egg for fertilization at the time of ovulation (your most fertile time)!

Once ovulation has occurred, Progesterone releases into the body, turning off the Estrogen hormone. This hormone switch spikes up BBT and thickens CM until it is not present any longer, lasting an approximate 12-16 days, until menstruation.

If the egg gets fertilized and you become pregnant, BBT will remain high for more than 18 days.

  • Conception can only occur during the fertile window
  • Abstinence, or barrier methods like condoms and withdrawal during the fertile window will prevent from unwanted pregnancy
  • Engaging in unprotected sex during the fertile window will increase chances of becoming pregnant

Basal Body Temperature (BBT)

A Basal Body Thermometer measures the temperature under your tongue immediately after waking up in the morning. It should be taken:

  • Daily, at the same time every morning, +/- one hour
  • After 3 consecutive hours of deep sleep
  • Before getting up out of bed to use the bathroom, communicating, any physical contact, etc.

Keep in mind that viral infections that cause fevers will affect Basal Body Temperature readings.

Cervical Mucus (CM)

Cervical Mucus is a vaginal secretion, commonly known to society as “discharge.” Next time you use the bathroom, check the gusset of your underwear (where your vulva touches). Usually the consistency will flow in a specific pattern over the course of approximately 14 days, but it varies from human to human!

Regularly check the gusset of your underwear throughout each day to observe an accurate quality and quantity of your CM.

How Much Does Fertility Awareness Cost?

A Basal Body Thermometer costs approximately $9 – $30.

The optional, but recommended, Taking Charge of Your Fertility by Toni Weschler costs approximately $20.

What Are The Side Effects?

You will not get any side effects by using the Fertility Awareness Method of birth control.

How Effective Is it?

99.7% Effective with perfect use, .3% Failure rate

76% Effective with typical use, 24% Failure rate

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Can A Woman Get Pregnant During Her Period?

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Yes and No.

It is highly uncommon for a woman to become pregnant during her period, although it IS possible!
Can a Woman Get Pregnant During Her Period

Artist: Elisa Reimer

The first day of Menstruation is Cycle Day 1 of each cycle and lasts approximately 3-8 days. Once it is over, the fertile window will begin on the first day of observed Cervical Mucus (CM).

Sperm could stay alive in the vagina for up to 5 days, if given the alkalized environment that cervical mucus brings.

Conception can only occur during ovulation

During ovulation, a mature egg will release from an ovary, move its way through the Fallopian tubes and embed itself into the nutritious uterine lining of the womb to be fertilized. This takes place within 24-48 hours.

Ovulation occurs around Cycle Day 14 (in relation to a 28 Day Cycle). If the egg does not become fertilized within the 24-48 hours, the Uterine Lining will shed 12-16 days later as your next period.

Some may experience spotting, or breakthrough bleeding, in between periods. Spotting could occur during ovulation and misled as a period, which sometimes makes it difficult to pinpoint Cycle Day 1. Track your cycles for at least 3 months to differentiate your Menstrual Phase versus Ovulation Phase. 

Can a woman get pregnant during her period?

  1. If you experience 24 or-less day cycles, ovulation could likely occur closer to the end of menstruation. The chances of conception during menstruation are much higher in this case versus within an average 28-32 day cycle.
  2. Conception could take place during your period if ovulation did not occur in your previous cycle.

Track your cycles daily for at least 3 months to understand:

  • Your average cycle length
  • If ovulation was confirmed in your previous cycle
  • Your Menstrual Phase versus Ovulation Phase
  • The probability of becoming pregnant during your period
Keep in mind

An ultrasound is the only way to predict the exact moment of ovulation, although Ovulation Predictor Kits (OPK’s) are a very common and effortless way to visually notice your fertile time. OPK’s are 99% effective in predicting ovulation to conceive.