During the menstrual cycle, the female hormones oestrogen and progesterone cause some observable effects and symptoms:
Observation of these changes provides a basis for periodic abstinence methods. There are three common techniques used in periodic abstinence methods, namely:
This method is the most widely used of the periodic abstinence techniques. The calendar method is a calculation-based approach where previous menstrual cycles are used to predict the first and the last fertile day in future menstrual cycles. This method requires a good understanding of the fertile and infertile phases of the woman's menstrual cycle. It is based on the regularity of the menstrual cycle and the fact that an ovum (egg) can only be fertilised within 24 hours of ovulation.
What do you know about the regular and irregular menstrual cycle of a woman?
A regular menstrual cycle is when monthly bleeding happens every month or 28 days.
An irregular menstrual cycle is when monthly bleeding is variable from month to month, for example it can vary from 25 to 32 days in some women.
It is important for you to know that before relying on this method a woman needs to record the number of days in each of her menstrual cycles for a period of at least 6–8 months (remembering that the first day of menstrual bleeding is always counted as day 1). See the box below on how to advise women using the calendar method.
For irregular cycles, identify the longest and the shortest cycles recorded over six to eight cycles.
A woman's last six menstrual cycles were 28, 26, 29, 27, 29 and 27 days. Using this information, calculate and instruct her about how to use the calendar method to prevent pregnancy.
Therefore, the fertile period of this client is between the 8th–18th days, so she should avoid sex during this period to prevent pregnancy.
However, if the client's menstrual cycle is regular and comes every 28 days or close to it, ovulation should occur about 14 days before the next period. For this reason, the woman should count backwards 14 days from her next period to calculate the day she will ovulate. Consequently, she should avoid sex from about seven days before that day until about two days after ovulation is expected.
A client comes to you and asks about using the calendar method to prevent pregnancy. When you ask her about the history of her menstrual cycle over the last six months, she tells you it comes regularly every 30 days. Calculate the fertile period of your client and advise her when to avoid sex in order to prevent pregnancy.
| Regular cycle | 30 - 14 = 16 |
| First day of fertile phase | 16 - 7 = 9 |
| Last day of fertile phase | 16 + 2 = 18 |
Therefore, her fertile period is between the 9th and 18th days, and she should avoid sex between these days of the cycle.
This method does not require daily monitoring of fertility indicators.
It is associated with a high failure rate and can be difficult to use in the case of irregular menstrual cycles. It also takes a long time to learn and use it properly.
This method is about 95% effective if a woman uses it correctly (Family Planning: A Global Handbook for Providers, World Health Organization (WHO), 2007).
What can a couple do if they are not confident about using this method?
The couple should be advised to use additional methods, like condoms or other barrier methods, to prevent unwanted pregnancy. You should provide them with the necessary resources.
The basal body temperature method is based on the slight increase in the body temperature of women at rest by about 0.3–0.5°C during and after ovulation, due to the action of an increased level of progesterone secreted by the corpus luteum. The rise in body temperature sustained for three consecutive days indicates that ovulation has occurred, and it remains at this increased level until the start of the next menstrual cycle. In this section you will learn about when the rise in body temperature occurs, and what women need to know in order to use this method properly.
This natural family planning method may be selected if the woman is not willing to touch her genitalia to check her cervical secretions (as in the cervical mucus method), but is willing to abstain from sexual intercourse with her spouse for long periods of time. It is difficult for a woman to use natural family planning methods if her menstrual cycle is irregular, as it may disturb the subtle changes in body temperature and cervical secretions, as a result of hormonal effects.
The advantages and disadvantages of BBT are summarised in the table below.
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Advantages |
Disadvantages |
|---|---|
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BBT is about 98% effective if the woman uses the method correctly (Family Planning: A Global Handbook for Providers, WHO, 2007). But it's still important to realise that of 100 women using this method in any one year, two will become pregnant. Its effectiveness will decrease dramatically to 80% if the woman does not use the method correctly. Effectiveness is greatest when the couple limits unprotected sexual intercourse to the period after ovulation.
To use the basal body temperature method effectively, you need to know and teach women how to read a thermometer and record the results on a special chart or graph paper. The figure below shows the period of time when a couple must avoid sexual intercourse or use other protective methods.
In the figure above, on which days of the woman's menstrual cycle does her temperature show a three-day rise?
It rises on days 15, 16 and 17. This indicates that ovulation has happened and passed.
If the temperature falls on or below the woman's normal basal temperature during the three day count, that may indicate ovulation has not yet occurred. To avoid pregnancy, wait until three consecutive temperatures are recorded above the normal basal temperature.
After the beginning of the infertile phase (the third day of a rise in temperature or 'peak day'), it is not necessary to take the temperature and it is possible to continue sexual intercourse until the first day of the next menstrual cycle.
In this regard, you should explain that the women needs to do the following:
How long does the ovum remain viable?
The ovum remains viable for at least 24 hours. It is important to note that because the woman cannot be sure exactly when she ovulated, she should be cautious about resuming sexual intercourse.
There is a lot of information in this section. You may wish to go through the basal body temperature method several times so that you are confident that you can explain it to couples who wish to practise this method. They will be more likely to follow the procedure carefully if they understand what is happening in the woman's body.
The cervical mucus method (or Billings method) is based on the recognition and interpretation of changes in cervical mucus and sensations in the vagina, due to the effect of changes in oestrogen levels during the menstrual cycle. This method is also an ovulation method used by women trying to get pregnant and have a child.
You may remember from the description of natural family planning methods, that the rise in the level of oestrogen during the menstrual cycle influences the cervical gland to secrete mucus that changes from a sensation of dryness in the vagina (characterised by thick, viscous and sticky mucus), to a sensation of wetness in the vulva (characterised by thin, white, slippery and stretchy thread-like, transparent strands — similar to uncooked egg white), during ovulation.
Using this method, these are the times when it is safe to have sexual intercourse:
The effectiveness of the cervical mucus method is about 97% if women use it correctly (Family Planning: A Global Handbook for Providers, WHO, 2007). The conditions which can affect correct use are summarised in the box below.
The advantages of this method are similar to those associated with the use of the basal body temperature method.
CMM has a high failure rate because it needs several days of abstinence and a lot of experience in using the method to be effective. It is also difficult to use this method in the case of vaginal infections, as the cervical mucus secretions may be misleading.
You will need to carefully instruct women to be able to:
| Approximate day of menstrual cycle (phase) | How to identify | Intercourse allowed? |
|---|---|---|
| 1‒5: Menstruation* | Bleeding | No |
| 6‒9: Dry days | Absence of cervical mucus | On alternate nights only, to avoid confusion between mucus and sperm |
| 10: Fertile day | Onset of sticky mucus secretions (gradually becoming slippery over the following days) | No |
| 16: Peak fertile day | Last day on which slippery mucus (resembling raw egg white) is observed | No |
| 20: Fertile period ends | Evening of the fourth day after the peak day | After fertile period ends |
| 21‒29: Safe period (dry days) | From end of fertile period until onset of bleeding | Yes |