Fertility Awareness (FA) is the practice of observing one or more of a woman’s primary fertility signs to determine the fertile and infertile phases of her cycle. Depending on their goals, couples may choose to time unprotected sexual intercourse so that it falls during the infertile phase (to avoid pregnancy) or the fertile phase (to achieve it). Avoiding pregnancy by using FA is sometimes called the Fertility Awareness Method (FAM).
Natural family planning (NFP) is a religiously motivated form of Fertility Awareness. It generally prohibits the use of contraceptive methods during the fertile phase of a woman’s cycle. NFP couples wishing to avoid pregnancy must abstain from sexual relations during that time.
The Calendar Method, also known as the Rhythm Method or the Knaus-Ogino Method (named after Hermann Knaus and Kyusaku Ogino), relies solely on counting days in order to estimate the onset of a woman's fertile period. This is NOT fertility awareness, though it is based on the same scientific principles. Because of its lower accuracy, many FA teachers consider calendar rhythm to have been obsolete for at least 20 years.
Couples interested in the use of FA may also be interested in the Lactational Amenorrhea Method (LAM) and Ecological Breastfeeding as ways to avoid pregnancy. These methods are also considered NFP if they are not combined with chemicals or devices.
This description is an overview only. Couples wishing to use Fertility Awareness to avoid pregnancy should seek instruction from an experienced teacher.
The three primary fertility signs are basal body temperature (BBT), cervical mucus, and cervical position. A woman practicing fertility awareness may choose to observe one sign, two signs, or, all three.
Basal body temperature is a person’s temperature taken when they first wake up in the morning (or after their longest sleep period of the day). In women, ovulation will trigger a rise in BBT between 0.3 and 0.9C (0.5 and 1.6°F) that lasts approximately until the next menstruation. Sixty percent of the time, ovulation happens the day before the temperature rise. The other forty percent of the time, ovulation may happen a few days in either direction. By the evening of the third day of the temperature rise, chances of pregnancy have dropped to less than 1% per year and ovulation is considered confirmed.
The appearance of cervical mucus and vulvar sensation are generally described together as two ways of observing the same sign. Cervical mucus is produced by the cervix, the muscle that separates the uterus from the vaginal canal. Chemically it is similar to seminal fluid. Cervical mucus promotes sperm life by decreasing the acidity of the vagina and providing nurishment to the sperm. Cervical mucus is a heterogeneous mixture of different types of mucus, several of which have specialized functions. One type of mucus has a structure that helps guide sperm into the cervix and then the uterus. The production of fertile cervical mucus is caused by the same hormone (estrogen) that prepares a woman’s body for ovulation. By observing her cervical mucus, and paying attention to the sensation as it passes the vulva (fertile cervical mucus can produce a sensation similar to a runny nose, or a general sensation of the vulva feeling slippery), a woman can detect when her body is gearing up for ovulation. When ovulation is immanent, estrogen production drops slightly and progesterone starts to rise. The rise in progesterone signal the cervix to start closing and to start producing a mucus plug. It also activates the Pockets of Shaw in the lower part of the vagina, which absorb water from the mucus. This causes a distinct change in the quantity and quality of mucus observed at the vulva. Once the cervix is closed and the egg is dead, a woman is infertile for the remainder of the cycle. Each of the methods of fertility awareness observes and interprets this occurence differently, and uses different rules to determine the onset of post-ovulatory infertility.
The cervix changes position in response to the same hormones that cause cervical mucus to be produced and to dry up. When a woman is in an infertile phase of her cycle, the cervix will be low in the vaginal canal; it will feel firm to the touch (like the tip of a person’s nose); and, the os – the opening in the cervix – will be relatively small, or ‘closed’. As a woman becomes more fertile, the cervix will rise higher in the vaginal canal; it will become softer to the touch (more like a person’s lips); and the os will become more open. After ovulation has occurred, the cervix will revert to its infertile position. No studies have been done to tie patterns in cervical changes with an exact day of ovulation. However, this sign is considered to correlate very well with BBT and cervical mucus observations.
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