This method (also known as the Fertility Awareness Method) involves recognizing
the periods during the month to avoid sex and when to have sex without
contraception with reduced risk of pregnancy. It requires a good understanding of
the body's ovulation cycle and consistent record-taking of between 6 to 12
months of monthly menstrual cycles.
Ovulation is said to occur when a woman's egg cell (Ovum) is released from the
ovaries. It occurs once a month, at about 12 - 16 days after menstruation(The
first day of menstruation usually signals the start of the monthly cycle).
Although the female ovum can probably be fertilized for only a few hours after
ovulation, the male sperm because of its lifespan, can fertilize the ovum for
several days after entering the cervical canal; thus, conception can actually
result from sex that occurs up to 5 days before ovulation.
To track menstrual cycle, determine ovulation and fertility period of a woman,
three types of the natural family planning method are frequently used, namely;
- Calender
Rhythm Method
- Measurement
of Basal Body Temperature Method
- Cervical
Mucus Method
- Symptothermal Method
Calender Rhythm Method
This method uses accurate records of past menstrual cycles
(at least 6 months record of menstrual cycle). To determine fertility, the
female subtracts 18 days from the length of her shortest recorded cycle (this
tells the first day fertility time commences) and 11 days from the longest
recorded cycle (this tells the last day of the fertility time). The duration of
time thus obtained from the first day fertility time commences to the last day
of the fertility time (as determined from the calculation) is her fertile
period.
Couples are to avoid sex during this fertile period or compulsorily use a
condom/diaphragm if sex cannot be avoided to prevent conception.
The calender rhythm method is the least effective of the natural family
planning methods due to variance in menstrual cycle lenghts. On the average,
women with monthly cycle lengths between 26 - 29 days must abstain from sex
from the 8th day of menstrual cycle all through to the 18th day. Greater
differences in cycle lengths will increase the required periods of abstinence
from sex,
Measurement of Basal Body Temperature Method
The measurement of basal body temperature is an effective method used in
determining ovulation and fertile period in a woman as basal body temperature
rises by about 0.5°C (or 0.9°F) after ovulation.
To do this the woman measures her body temperature with a thermometer before
getting out of bed everyday. Temperature readings must be taken same time every
morning and recorded. She should watch for a rise in her body temperature by
about 0.5°C. This occurs immediately after ovulation.
The couple are to avoid sex for at least 72 hours after this rise in
temperature.
Cervical Mucus Method
The cervical mucus method serves as an accurate indicator of fertility
period as an increase in cervical mucus usually occurs near the time of
ovulation. The hormone that controls menstrual cycle in women also makes the
cervix produce mucus. This mucus which collects in the vagina undergo changes
in quantity and quality just before and during ovulation.
To use the cervical mucus method the woman needs to
recognize these changes and mucus patterns. They include;
- At
start of menstrual cycle, menstrual blood flow covers mucus, so no mucus
is seen.(Unsafe period)
- After
menstrual blood flow end, there are a few days without mucus (dry days).
These are infertile (safe) periods if a woman has long menstrual cycle
(not safe if menstrual cycle is short)
- Once
an ova (female egg cells) starts to ripen at the ovaries more mucus is
produced. It appears at the vagina as a thick, cloudy, yellow or white
coloured mucus. They also feel sticky.(Unsafe periods)
- Mucus
secretion is highest just before ovulation and it appears like raw egg
white, easily stretched with the fingers. The days this occurs are refered
to as wet days and signifies the fertility (Unsafe) period in the woman.
- Wet
days last for about 4 days (Unsafe period). After that mucus secretions
become cloudy again and feel sticky until it finally dries out (dry days).
These (dry days) are infertile (safe) periods until the next menstrual
bleeding starts.
It must be noted that the woman's mucus secretions is often altered by breastfeeding, hormonal contraceptives, emergency contraceptives and sexually transmitted infections. These change agents should be avoided when using the cervical mucus method
Once all these changes are understood, the woman will have sex during the safe periods and abstains from unprotected sex during the unsafe periods (as indicated above).
Symptothermal Method
This is the most accurate of the natural family planning methods as it combines
the measurement of basal body temperature method and the cervical mucus method
with other fertility signs such as presence of breast tenderness and ovulatory
pain in determining fertility and periods of abstinence from sex.
Couples avoid sex between the first day of menses and either the fourth day of
peak cervical mucus secretions (wet days as explained above) or the third day
after the rise in basal body temperature.
The symptothermal method, when implemented correctly is 90% effective
as a contraceptive method.