What Is It?
The S-T Method allows couples to identify fertile and infertile phases of menstrual cycle. The S-T method still uses cervical mucus changes at the vulva and also combines a temperature monitoring component to confirm when ovulation has occurred. Signs of infertility include a noticeable rise in morning body temperature from baseline, disappearance of mucus at the vulva, and infertile cervix signs.
What is the Pre-Ovulatory Phase?
Begins on the first day of menstruation until ovulation occurs. It is variable in length and may range from 9-21 days. Usually a woman will feel dry and have no cervical mucus secretion after menstruation known as dry days or a basic infertile pattern however this depends on the length of her cycle. Fertility begins when there is a change in the basic infertile pattern where there is the first sensation of dampness, stickiness or a thick, opaque, white or yellowish mucus. Estrogen stimulates cervical mucus to become more clear, abundant and flowing to vulva.
When Does Ovulation Occur?
Just before ovulation, mucus becomes more transparent like raw egg whites and produces a characteristic lubricative sensation. The sensation of lubrication is more important than the amount or physical presence of mucus since the mucus may be so fluid-like that it may not be detectable. The peak day is defined as the last day when the mucus produces a high fertile sign by its sensation, appearance or fluidity.
What is the Post-Ovulatory Phase?
Extends from ovulation until the next menstruation. Due to the influence of progesterone, the cervix becomes firmer and the cervical opening smaller. Cervical mucus may disappear or resume to its earlier characteristics (sticky, thick, damp). If using cervical mucus alone, count three days after the peak day before the definite infertile phase begins.
The S-T Method allows couples to identify fertile and infertile phases of menstrual cycle. The S-T method still uses cervical mucus changes at the vulva and also combines a temperature monitoring component to confirm when ovulation has occurred. Signs of infertility include a noticeable rise in morning body temperature from baseline, disappearance of mucus at the vulva, and infertile cervix signs.
What is the Pre-Ovulatory Phase?
Begins on the first day of menstruation until ovulation occurs. It is variable in length and may range from 9-21 days. Usually a woman will feel dry and have no cervical mucus secretion after menstruation known as dry days or a basic infertile pattern however this depends on the length of her cycle. Fertility begins when there is a change in the basic infertile pattern where there is the first sensation of dampness, stickiness or a thick, opaque, white or yellowish mucus. Estrogen stimulates cervical mucus to become more clear, abundant and flowing to vulva.
When Does Ovulation Occur?
Just before ovulation, mucus becomes more transparent like raw egg whites and produces a characteristic lubricative sensation. The sensation of lubrication is more important than the amount or physical presence of mucus since the mucus may be so fluid-like that it may not be detectable. The peak day is defined as the last day when the mucus produces a high fertile sign by its sensation, appearance or fluidity.
What is the Post-Ovulatory Phase?
Extends from ovulation until the next menstruation. Due to the influence of progesterone, the cervix becomes firmer and the cervical opening smaller. Cervical mucus may disappear or resume to its earlier characteristics (sticky, thick, damp). If using cervical mucus alone, count three days after the peak day before the definite infertile phase begins.
How to Avoid Pregnancy?
1) Only have intercourse during the post-ovulatory phase where infertility is definite.
2) The is a minimal chance of pregnancy when sexual intercourse occurs during the relative infertile phase directly after menstruation. The length of the relative infertile phase is calculated based on previous cycle lengths.
When is the Relative Infertile Phase?
Some women have a phase of infertility starting on the first day of menstruation until the first sign of fertility based on symptoms. Sexual intercourse during the relative infertile phase is minimal however conception increases towards the end of this phase. The duration of the relative infertile phase is determined by monitoring the presence of fertile symptoms and using a simple calculation (whichever indicates the shortest relative infertile phase takes priority). By using the following calculations, the number indicates the last day of the relative infertile phase:
When is the Definite Infertile Phase?
Sexual intercourse during this phase has no chance of conception occurring. When the temperature rises and the fertile symptoms subside, use the following steps:
Note exceptions: the rules of identifying the infertile phase cannot be used when discontinuing hormonal contraceptives, during pre-menopause, after childbirth, breastfeeding, miscarriage and with highly erratic charting results.
How to Interpret Changes in Cervical Mucus?
Both the sensation and appearance are monitored and recorded. Some descriptors for sensation that cervical mucus produces at the vulva (outer vagina) include dryness, moist, sticky, wet, lubrication. Some descriptors for cervical mucus appearance include opaque, cloudy, transparent, white, thready and yellow. If sexual intercourse occurs, the woman must learn how to distinguish seminal fluid discharge from cervical mucus for accurate charting.
How to Interpret Changes in Basal Body Temperature (BBT)?
Body temperature is affected by many factors including the hormonal changes which occur during the menstrual cycle. In order to obtain an accurate BBT trend, a woman may take her body temperature at approximately the same time each morning when her body is at rest and record it on a chart. In the pre-ovulatory phase the body temperature will remain at a lower level. Near ovulation the body temperature typically rises 0.2-0.5 degrees Celsius known as a shift over one to four days. After ovulation the body temperature will remain at a higher level until the next menstruation.
How to Measure Basal Body Temperature?
Purchase a basal mercury or electronic thermometer with a 1/10th degree scale and an accuracy of +/- 0.1 degrees Celsius. This type of thermometer can be found at most community pharmacies. Pay close attention to follow the operating instructions (ex. do not rinse with warm/hot water, use to measure fever, expose to direct heat or drop etc). Site of temperature measurement include oral, vaginal or rectal (vaginal or rectal preferred due to higher accuracy). Stay consistent with a temperature measurement method to avoid fluctuations. It is best to take the measurement within five minutes of waking each day and avoid activity beforehand. If a temperature is delayed by more than one hour, this should be noted and potentially be considered an outlier reading. Also at least one hour of rest is needed before taking a reading. Any prolonged sleep disturbance or change in sleep routine during the night should be noted since this can affect the temperature reading.
What symptoms are monitored?
In addition to cervical mucus and BBT measurements, several other symptoms are recorded. These symptoms include changes in the cervix, abdominal pain, spotting, sensitive breasts, and other symptoms.
- Cervical changes: detected by a woman doing self-palpitation. This is done by washing her hands and inserting her index or middle finger into her vagina up to the top where the cervix is located. She will feel a smooth sphere at the end of the vagina with a ridged wall. Observations include the location of the cervix, height, length, degree of opening, hardness, shape, and angle to the vaginal wall. In an infertile phase, the cervix will be low, closed, firm and tilted. During fertility the cervix changes to become high, open, soft and straight. All daily observations are noted on a S-T chart however as a woman becomes more experienced she may choose to only monitor the cervix during the fertile phase. It is recommended to palpitate the cervix at the same time each day in the evening to avoid disturbing mucus at the vulva.
- Abdominal pain: some women feel a pain either in the full abdominal area or on one side. The pain is often dull, diffuse and like a persistent ache or a sudden jab. These symptoms should be noted on her S-T chart and interpret alongside cervical mucus and temperature changes.
- Spotting: During ovulation, a spotting of pink, red, or brown bloody discharge may occur. Care should be taken not to interpret spotting as a menstrual event. If pregnancy is being avoided than intercourse should not occur during any bleeding event. The presence of a temperature rise may help confirm if ovulation has occurred.
- Sensitive breasts: some women may experience a breast sensation described as heavy, grainy, or irregular around or after ovulation. If these changes occur each cycle, it can be used as another indicator that ovulation has occurred along side a rise in temperature.
- Other: each women may have unique changes which she may notice during each cycle which may include skin eruptions, migraines, nausea, body odour, sexual desire, depressed feeling etc. They should only be used to indicate fertility status if they occur regularly and are combined with other objective signs such as cervical mucus and BBT shifts. Other events which should be charted include menstruation, intercourse, infection, fever, disease, medications and other changes in daily routine. Several factors such as trips, change in climate, excessive fatigue, late outings, excessive use of alcohol, lack of sleep and emotional shock can throw off accurate BBT measurements.
Reference:
1) Parenteau-Carreau, M.D. Planning Your Family the ST WAY. Serena Canada.1987: 1-80.
1) Only have intercourse during the post-ovulatory phase where infertility is definite.
2) The is a minimal chance of pregnancy when sexual intercourse occurs during the relative infertile phase directly after menstruation. The length of the relative infertile phase is calculated based on previous cycle lengths.
When is the Relative Infertile Phase?
Some women have a phase of infertility starting on the first day of menstruation until the first sign of fertility based on symptoms. Sexual intercourse during the relative infertile phase is minimal however conception increases towards the end of this phase. The duration of the relative infertile phase is determined by monitoring the presence of fertile symptoms and using a simple calculation (whichever indicates the shortest relative infertile phase takes priority). By using the following calculations, the number indicates the last day of the relative infertile phase:
- < 3 known cycles = no relative infertile phase
- 3-5 known cycles = shortest cycle - 22
- 6-11 known cycles = shortest cycle - 21
- > 12 known cycles = shortest cycle - 20
When is the Definite Infertile Phase?
Sexual intercourse during this phase has no chance of conception occurring. When the temperature rises and the fertile symptoms subside, use the following steps:
- Remove temperatures with a known disturbance noted on chart (outliers).
- Locate the highest normal temperature of the low pre-ovulatory temperatures.
- Draw a horizontal (cover) line across the chart on the printed line immediately above the point mentioned above (at least six temperature points are needed).
- Count three consecutive normal temperatures above the cover line. The definite infertile phase begins on the morning of the third day of high temperature (as long as infertile symptoms persist) and lasts until the next menstruation.
Note exceptions: the rules of identifying the infertile phase cannot be used when discontinuing hormonal contraceptives, during pre-menopause, after childbirth, breastfeeding, miscarriage and with highly erratic charting results.
How to Interpret Changes in Cervical Mucus?
Both the sensation and appearance are monitored and recorded. Some descriptors for sensation that cervical mucus produces at the vulva (outer vagina) include dryness, moist, sticky, wet, lubrication. Some descriptors for cervical mucus appearance include opaque, cloudy, transparent, white, thready and yellow. If sexual intercourse occurs, the woman must learn how to distinguish seminal fluid discharge from cervical mucus for accurate charting.
How to Interpret Changes in Basal Body Temperature (BBT)?
Body temperature is affected by many factors including the hormonal changes which occur during the menstrual cycle. In order to obtain an accurate BBT trend, a woman may take her body temperature at approximately the same time each morning when her body is at rest and record it on a chart. In the pre-ovulatory phase the body temperature will remain at a lower level. Near ovulation the body temperature typically rises 0.2-0.5 degrees Celsius known as a shift over one to four days. After ovulation the body temperature will remain at a higher level until the next menstruation.
How to Measure Basal Body Temperature?
Purchase a basal mercury or electronic thermometer with a 1/10th degree scale and an accuracy of +/- 0.1 degrees Celsius. This type of thermometer can be found at most community pharmacies. Pay close attention to follow the operating instructions (ex. do not rinse with warm/hot water, use to measure fever, expose to direct heat or drop etc). Site of temperature measurement include oral, vaginal or rectal (vaginal or rectal preferred due to higher accuracy). Stay consistent with a temperature measurement method to avoid fluctuations. It is best to take the measurement within five minutes of waking each day and avoid activity beforehand. If a temperature is delayed by more than one hour, this should be noted and potentially be considered an outlier reading. Also at least one hour of rest is needed before taking a reading. Any prolonged sleep disturbance or change in sleep routine during the night should be noted since this can affect the temperature reading.
What symptoms are monitored?
In addition to cervical mucus and BBT measurements, several other symptoms are recorded. These symptoms include changes in the cervix, abdominal pain, spotting, sensitive breasts, and other symptoms.
- Cervical changes: detected by a woman doing self-palpitation. This is done by washing her hands and inserting her index or middle finger into her vagina up to the top where the cervix is located. She will feel a smooth sphere at the end of the vagina with a ridged wall. Observations include the location of the cervix, height, length, degree of opening, hardness, shape, and angle to the vaginal wall. In an infertile phase, the cervix will be low, closed, firm and tilted. During fertility the cervix changes to become high, open, soft and straight. All daily observations are noted on a S-T chart however as a woman becomes more experienced she may choose to only monitor the cervix during the fertile phase. It is recommended to palpitate the cervix at the same time each day in the evening to avoid disturbing mucus at the vulva.
- Abdominal pain: some women feel a pain either in the full abdominal area or on one side. The pain is often dull, diffuse and like a persistent ache or a sudden jab. These symptoms should be noted on her S-T chart and interpret alongside cervical mucus and temperature changes.
- Spotting: During ovulation, a spotting of pink, red, or brown bloody discharge may occur. Care should be taken not to interpret spotting as a menstrual event. If pregnancy is being avoided than intercourse should not occur during any bleeding event. The presence of a temperature rise may help confirm if ovulation has occurred.
- Sensitive breasts: some women may experience a breast sensation described as heavy, grainy, or irregular around or after ovulation. If these changes occur each cycle, it can be used as another indicator that ovulation has occurred along side a rise in temperature.
- Other: each women may have unique changes which she may notice during each cycle which may include skin eruptions, migraines, nausea, body odour, sexual desire, depressed feeling etc. They should only be used to indicate fertility status if they occur regularly and are combined with other objective signs such as cervical mucus and BBT shifts. Other events which should be charted include menstruation, intercourse, infection, fever, disease, medications and other changes in daily routine. Several factors such as trips, change in climate, excessive fatigue, late outings, excessive use of alcohol, lack of sleep and emotional shock can throw off accurate BBT measurements.
Reference:
1) Parenteau-Carreau, M.D. Planning Your Family the ST WAY. Serena Canada.1987: 1-80.