Contraception: natural family planning
What is natural family planning?
Natural family planning is a birth control option that involves abstaining from having sexual intercourse during the time that you are most likely to become pregnant. It is also sometimes referred to as ‘periodic abstinence’ and includes such techniques as the ‘Billings’ and ‘rhythm’ methods.
How does it work?
The natural family planning method works by determining your fertile days by observing changes in your basal body temperature (BBT) or cervical mucus, or by using sympto-thermal (involving ovulation symptoms and temperature observation) or calendar methods, and by refraining from intercourse during those days.
Because some sperm can survive for as long as 7 days (the average is 2-3 days), and eggs for up to 24 hours after release from the ovary, most women are fertile for a few days before and after ovulation, and this must be taken into account in determining the period of abstinence.
How effective is it?
The effectiveness of natural planning methods can vary enormously depending upon the particular technique used, and the commitment of the couple. When used for a year by 100 women, the different methods have the following failure rates: the temperature method will result in 14-24 pregnancies; the mucus method 20 pregnancies; and the sympto-thermal method 16 pregnancies. The calendar method has a high failure rate, and is generally not recommended.
What are the advantages?
Some of the advantages of natural family planning are that:
- it does not require medicines, chemicals or devices;
- there are no health risks;
- it is approved by many religions;
- it is inexpensive;
- it can encourage communication and co-operation in motivated couples; and
- it allows a woman to become aware and informed of her reproductive cycles.
What are the disadvantages?
Some of the disadvantages of natural family planning are that:
- it requires extensive instruction and many steps to predict ovulation (fertile period);
- couples must be highly motivated;
- it may result in periods of sexual frustration during periods of abstinence;
- since the length of menstrual cycles and the day of ovulation may vary each month, the timing of intercourse must be adjusted accordingly; and
- in practice, it is not as reliable as other methods of birth control.
How is it used?
The way that you use natural family planning depends upon the technique you choose to monitor your menstrual cycle.
Temperature method
To use the temperature method, you should take your basal body temperature (BBT) at the same time every day upon waking, and before getting out of bed, eating or drinking. This can be done vaginally, rectally or orally (the least accurate) with a special basal or ovulation thermometer that can give an accurate measurement to within one-tenth of a degree (0.1 Celsius). Factors that can skew these recordings include sleeping in (false high), having too little sleep (false low), illness (false high), consuming alcohol the night before (false high), or having your electric blanket on high (false high).
If you chart your daily temperature, you will notice that following ovulation your BBT will rise by 0.2-0.4 degrees Celsius. Once you have recorded 3 consecutive temperature rises (all of which exceed the previous 6 recordings), you can safely have intercourse. This means that you can only have sex in the phase of your menstrual cycle after ovulation (i.e. for about 12 out of 28 days).
Mucus (Billings) method
To use the mucus (Billings) method, you must learn to distinguish between your fertile and infertile days on the basis of the type of cervical mucus being produced by your body. During the first part of your cycle (immediately after your period — the infertile phase) you will have a feeling of vulval dryness. This is followed by a period of vulval wetness, where your body produces clear, stretchy, slippery mucus, which corresponds to ovulation (fertile phase). A post-ovulatory phase then occurs when progesterone is produced, which causes the vulval area to have thicker, cloudier mucus, before returning to dryness once again.
You should mark these changes on a chart, indicating your fertile peak (last day of the slippery mucus) with a cross and numbering the 3 days following it. Charts can be obtained from some Family Planning and women’s health centres. You should not have sexual intercourse during this fertile phase, and until 3 consecutive dry days have passed. You should not have sexual intercourse during your period. Also, if you have sex after your period and before the fertile peak it should only be on alternate evenings where no mucus is present, otherwise the semen will make it impossible to determine the status of your mucus.
Sympto-thermal method
This method uses a combination of the above two techniques, with temperature being taken in the morning, and mucus being examined in the evening. Sometimes it is used in conjunction with other signs of ovulation, such as mid-cycle pain or breast tenderness.
Calendar (rhythm) method
This method is based on the assumption that ovulation takes place 12-16 days before your period starts. Knowing the length of your last 6 menstrual cycles, you can use this information to roughly predict when you should abstain from sexual intercourse — but only with an accuracy of 82 per cent for your next 3 cycles. This method is generally not recommended because of its unreliability.
Last Reviewed: 01 May 2002
