The length of a menstrual cycle is measured from the first day of menstruation, ie fresh red bleeding, up to, but not including, the first day of the next menstruation. The normal cycle length varies widely in healthy women and even in the same woman at different stages of her life.

Fertility awareness methods of contraception include all methods that are based on the identification of the fertile days of the menstrual cycle.

FERTILITY awareness is a term for individuals’ understanding of their reproductive anatomy and physiology in relation to fertility.

In the case of a woman, it includes identification of the fertile time during the menstrual cycle. In the case of a male, it includes understanding of his reproductive potential. In the case of a couple, it includes the development of a shared understanding about their fertility potential at different stages of their lives and their ability to communicate about fertility issues with one other and healthcare professionals.

Fertility awareness methods (FAM) of contraception include all methods that are based on the identification of the fertile days of the menstrual cycle (fertile time), which is at or about the time when the ovary releases the egg (ovulation). FAM works by keeping sperm out of the vagina during the fertile time.

The effectiveness of these methods depend on two important variables – the identification of the fertile time and the modification of sexual behaviour during this time. Couples can either abstain from vaginal intercourse or use a barrier method correctly during the fertile time.

FAMs are suitable for individuals or couples who do not find other methods of avoiding pregnancy acceptable because of personal, cultural or religious reasons.

Fertility pattern

In order to know when one is most likely to get pregnant, a woman has to be familiar with her menstrual cycle.

Pregnancy occurs when the woman’s egg is fertilised by the man’s sperm. There are days in the menstrual cycle when fertilisation can occur and there are days when they cannot. There are some days when fertilisation is unlikely but still possible. Vaginal intercourse during the days when it is possible for fertilisation (fertile time) is necessary for pregnancy to occur.

The length of a menstrual cycle is measured from the first day of menstruation, ie fresh red bleeding, up to, but not including, the first day of the next menstruation. The normal cycle length varies widely in healthy women and even in the same woman at different stages of her life.

The fertile time depends on the length of the cycle. The ovary invariably releases an egg (ovulation) about 12 to 14 days before the next menstruation. The time before ovulation, however, is more variable.

The fertile time depends on the life spans of the egg and the sperm, which are about 17 hours and seven days respectively. Fertilisation must take place during those few hours after ovulation if pregnancy is to occur. Various studies reported that nearly all pregnancies occurred within a six day fertile window.

The fertility pattern varies in different women. Some women have different fertility times in different months of their menstrual cycles.

The advantages of FAMs include the planning and avoidance of pregnancy; acceptability to all religions and cultures; absence of physical side effects; and no use of chemical agents or physical devices.

It is relatively cheap and educational as it promotes fertility awareness. It encourages shared responsibility and increases communication. It is effective provided the user is taught well and follows the instructions given.

The disadvantages include the keeping of daily records, which some women find difficulty with; taking at least three to six menstrual cycles for effective learning; abstinence or use of a barrier method during the fertile time, which some couples find difficulty with; and no protection against sexually transmitted infections.

Its success depends on strong commitment by both partners all the time. Events like illness, stress, shift work and travel may make the interpretation of fertility indicators more difficult. The fertility monitoring devices are relatively more expensive than other more effective family planning methods.

The fertile time can be identified by observation of physiological indicators, calculations based on cycle length or fertility monitoring devices.

Physiological indicators method

The physiological indicators of the fertile time include basal body temperature, cervical secretions and changes in the cervix that occur in response to the changes in the levels of oestrogen and progesterone during the menstrual cycle.

These indicators may be used alone or in combination to improve effectiveness.

Progesterone causes an increase in basal body temperature (BBT, or waking temperature), which is the temperature before getting out of bed and after resting for at least three hours.

As soon as ovulation occurs, progesterone increases the BBT by at least 0.2 degrees Celsius (0.4 degrees Fahrenheit). The higher temperature is maintained until the progesterone level falls at menstruation.

The temperature needs to be charted, using a fertility or digital thermometer, every day upon awaking in the morning (before eating or drinking).

The temperature chart does not identify the start of the fertile time. The fertile time ends after the temperatures recorded for three days in a row are higher than all the previous six days. This means that couples using BBT as a single indicator method have to abstain from intercourse from the beginning of menstruation until they have recorded three successive temperatures of at least 0.2 degrees Celsius higher than the preceding six days.

It is important to remember that the temperature can change because of reasons other than ovulation, eg if the temperature is taken earlier or later than usual, if there is an illness like flu or cold (the temperature can go up), or if painkillers are taken (the temperature can go down).

When used on its own, BBT’s overall failure rate is 5.4%, ie 5.4 pregnancies in 100 women in one year of use. It is only effective if used by highly motivated couples able to tolerate at least two weeks of abstinence because they have to abstain from the start of the cycle until after the temperature increase.

Cervical secretions are influenced by oestrogen and progesterone. After menstruation, when the oestrogen levels are low, there are no secretions, or they are minimal, thick, white and sticky, leading to rapid destruction of sperm by the acidic environment of the vagina.

With increasing levels of oestrogen, the cervical secretions increase in amount and become clearer, wetter, slippery and stretchy, like the white of a raw egg, leading to facilitation of sperm movements.

The fertile time starts when the woman is first aware of any cervical secretions. The last day of the transparent, wet and slippery secretions (peak day) coincides closely with ovulation.

With ovulation, the cervical secretions thicken, under the influence of progesterone, to form a thick plug, which does not favour sperm penetration. The peak day is only recognised on the day after the peak when the cervical secretions have become cloudy and thick.

The fertile time ends on the fourth morning after the peak day.

A study by the World Health Organization (WHO) reported that 94% of women could detect changes in cervical secretions indicating the start of the fertile time. Most women need to observe these changes for at least three months before they can recognise the changes with some degree of confidence.

It is important to remember that the changes in cervical secretions can be affected by semen, vaginal infections or spermicides.

When used on its own, the overall failure rate is about 20%, ie 20 pregnancies in 100 women in one year of use.

Changes in the muscle and connective tissue of the cervix are influenced by oestrogen and progesterone. These changes can be recognised by gently feeling the cervix with the fingers at about the same time every day.

The fertile time starts at the first sign of the cervix becoming soft, open or high. It ends after the cervix has been firm, closed and low for three days.

It will take several months to gain confidence in making out the cervical changes. These changes are of value in women with long menstrual cycles, during breastfeeding, and around the time of the menopause.

Although there are reports that these changes correlate with the cervical secretion and BBT in identifying the fertile time, there are no studies of the effectiveness of using the cervical changes as an indicator alone.

Oestrogen and progesterone also cause other recognisable changes – mid-cycle abdominal pain or spotting, abdominal heaviness, breast changes, and changes in desire and mood. Although the changes may be consistent in some individuals, they cannot be depended upon. Some of these changes may be symptoms of underlying medical conditions, which require treatment.

Cycle length method

The length of the menstrual cycle can also help detect the fertile time. This requires a record of the menstrual cycle for at least six months.

A WHO study reported that in women whose menstrual cycle lengths are between 26 and 32 days, the fertile time is likely to occur from days eight to 19 of the cycle, day one being the first day of menstruation (first day of fresh red bleeding). Further studies are needed to determine its effectiveness and acceptability to users.

The calculation method based on previous cycle lengths takes into consideration the survival time of the egg and the sperm. It is based on the length of a woman’s previous six to 12 menstrual cycles.

From a record of at least the previous six cycles, 20 days is subtracted from the shortest cycle to give the first fertile day, and 10 days is subtracted from the longest cycle to give the last fertile day.

If the longest or shortest menstrual cycle length changes, a recalculation has to be made. The reported failure rates vary from 5-47%, with an overall failure rate of about 20%, ie 20 pregnancies in 100 women in one year of use.

The Standard Days Method can be used by women with menstrual cycle lengths between 26 and 32 days, with the fertile time likely to occur within days eight to 19 of the cycle. Arevalo, Jennings and Sinai reported a probability of pregnancy of 4.75% over 13 cycles with correct use of the method, and 11.96% probability of pregnancy with typical use.

Fertility monitoring devices

Different fertility monitoring devices can provide the user useful information about her fertile time. The devices include hormone monitoring systems, computerised thermometers, luteinizing hormone sticks and saliva testing devices.

There is large variation in the pricing and effectiveness of these devices. A discussion with the doctor is advisable if you’re considering fertility monitoring devices.

A combination of FAM methods improves the accuracy in predicting the fertile time. One method can confirm that of the other, eg cervical secretions are helpful if the BBT is affected by sickness.

The common combined methods include BBT, cervical secretions and cycle length. The commonest combination is the symptom-thermal method, which involves BBT and cervical secretions.

The effectiveness of combined methods is more than that of a single method. Successful use requires a high degree of motivation. A recent study of combined methods reported an overall failure rate of 2.6%, i.e. 2.6 pregnancies in 100 women in one year of use.

Lactational amenorrhoea method

Breastfeeding reduces fertility because ovulation is suppressed by the raised prolactin levels during breastfeeding. A woman has effective protection against pregnancy in the first six months after giving birth if she has no periods and the baby is breastfed all the time, ie the baby is not given other food or drink.

Another contraceptive method has to be used when the periods return or the baby gets to six months of age or is given other food or drink regularly.

The failure rate of the lactational amenorrhoea method is 2%, ie two pregnancies in 100 women in one year of use.

Dr Milton Lum is a member of the board of Medical Defence Malaysia. This article is not intended to replace, dictate or define evaluation by a qualified doctor. The views expressed do not represent that of any organisation the writer is associated with. For further information, e-mail starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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