The basal temperature (BT) method is one of the ways to track fertile days, which are considered the most favorable for conception. Many women, when planning a pregnancy, use it with success. It is also interesting because it can determine the presence of ovulation, or its absence, evaluate the work of the ovaries, suggest a possible pregnancy a few days after ovulation, and also monitor its development for the first 12-14 weeks.
What is basal temperature?
Basal temperature is called the temperature, which is measured using a thermometer orally, vaginally, or, most often, rectally (in the rectum) at rest after a night’s sleep. During the menstrual cycle, body temperature, under the influence of certain hormones, changes.
In the first phase of the cycle (follicular), from the end of menstruation to the beginning of ovulation, hormones estrogen dominate in the body. During this period, egg maturation occurs. The average basal temperature of the first phase is in the range of 36 - 36.5C. And its duration depends on the time of maturation of the egg. For some, it can ripen for 10 days, and for others, all 20.
A day before the moment of ovulation, the value of BT for one day is reduced by 0.2-0.3C. And during ovulation itself, when the ripened egg leaves the follicle and a large amount of the hormone progesterone enters the body, BT should make a jump of 0.4-0.6С in one to two days, reach 37.0-37.2С and stay within these limits the entire luteal phase.
During the ovulation period, the dominant role of hormones changes (estrogens give way to progesterone). The most successful period for conception is 3-4 days before the start of ovulation (sperm viability) and 12-24 hours after ovulation. If during this period the egg does not merge with the sperm, it dies.
The second, luteal phase, passes under the influence of the hormone progesterone. It is produced by the corpus luteum, which appears in place of the bursting follicle. The luteal phase lasts from 12 days to 16. BT throughout the entire phase remains above 37.0 C, and if pregnancy does not occur, a day or two before the onset of menstruation, it decreases by 0.2-0.3 C. During menstruation, an unfertilized egg is expelled from the body along with an endometrial layer that is already unnecessary in this cycle.
It is believed that normally the difference between the average values of the two phases of the menstrual cycle should be at least 0.4C.
How to measure basal temperature
According to the rules, the basal temperature is measured in the mornings, at the same time (deviation of 20-30 minutes is allowed), without getting out of bed, avoiding sudden movements. Therefore, to prepare a thermometer - shake it off and put it near the bed, it is necessary in the evening.
If you have chosen any method of measuring basal temperature, for example, rectal, you must adhere to it the whole cycle. The thermometer is held for 5-7 minutes. It is better to start measuring the temperature from the sixth day after the first day of menstruation.
Data can be recorded on a piece of paper, and then, connecting the dots together, get a graph. Or keep charts online. For this, there are special programs that are convenient to use. The most difficult thing to do is to correctly measure the BT and enter the indicators into a spreadsheet. Next, the program itself will calculate the time when ovulation occurred (if it was), draw a graph, calculate the temperature difference between the two phases.
If you had to get out of bed at night, measure BT after 5-6 hours. Otherwise, the indicators will be uninformative and on this day you can ignore them. It is also worth not taking into account the days when you fell ill, and your body temperature has been increased.
It would be much simpler if it was possible to measure a simple body temperature, rather than basal. The difficulty is that the temperature of the body during the day can vary from stress, cold, heat, physical exertion, etc. Therefore, it’s very difficult to catch a period when body temperature would be informative. Therefore, it was decided to measure the basal temperature - after 5-6 hours of sleep at rest.
Basal temperature during pregnancy
As already mentioned above, the most favorable period for conception is a few days before and one day after ovulation. If pregnancy has occurred, the corpus luteum will produce progesterone up to 12-14 weeks. The basal temperature all this time will stay above 37C, it will not fall before the days of menstruation.
Some women, during pregnancy, stop measuring BT. This is not recommended, as BT during this period is very informative and allows you to control pregnancy.
With the onset of pregnancy, BT is kept above 37C, the permissible deviation is 0.1-0.3C. If in the first 12-14 weeks the BT values fall below normal for several days in a row, it is likely that the embryo is at risk. Probably progesterone deficiency is present. It is necessary to immediately consult a doctor to take appropriate measures. It will not be superfluous to be examined on an ultrasound machine.
If BT has risen above 38C, this also does not bode well. It can talk about the presence of infections in the woman's body or the onset of inflammatory processes. Based on a single decrease or increase in BT, conclusions should not be made, because perhaps mistakes were made in its measurement, or extraneous factors such as stress, the general condition of the body, etc., affected the value.
After 12-14 weeks it is already possible not to measure the basal temperature, because the indicators are not informative, because by this time the hormonal background of the pregnant woman is changing. Progesterone begins to produce a mature placenta, and the corpus luteum fades into the background.
Graph of basal temperature during pregnancy
If you record basal temperature readings on paper, or keep a graph on the Internet, you can pay attention to certain signs that signal that a pregnancy has occurred:
- on the 5-10th day (usually 7) after ovulation, BT for one day decreases by 0.3-0.5C. As they say, implantation retardation occurs. At this time, the embryo first tries to invade the uterine endometrium, i.e. find a place and take root. Often during this period, women notice minor bleeding within 1-2 days, it is called implantation. Sometimes it looks more like a cream or light brown daub;
- the temperature of the second phase tends to a mark above 37C;
- before the expected critical days, the basal temperature does not fall, but still rises by 0.2-0.3 ° C, on the graph it stands out as the third phase;
- critical days did not come on time, BT continues to stay at a high level for more than 16 days after ovulation. You can do the first test and see the result. It is likely that he will show two stripes.
Do not be upset if your schedule does not look like a classic pregnant. There are schedules by which it is impossible to determine the signs of pregnancy, but she, nevertheless, has come.
Elevated or decreased basal temperature
An ideal BT schedule should look like a flying bird with spread wings. The temperature difference between the two parts should be at least 0.4 C. Sometimes there are deviations from the ideal, which can indicate certain malfunctions in the woman’s body.
If the readings of the second phase of the cycle are normal, and the values of the first phase are higher than normal, this signals estrogen deficiency. And if it is much lower than normal, then on the contrary, about an overabundance of estrogen. What is one of the causes of infertility. Only in the first case it speaks of a thin endometrium, and in the second - the existence of follicular cysts.
If the indicators of the first phase are normal, and the values of the second phase are below normal, this indicates a lack of progesterone (pregnancy hormone). In this case, pregnancy can occur, but not hold. Therefore, to correct the situation, drugs containing progesterone are prescribed, which should be taken strictly under the supervision of a doctor.
If both phases of the cycle are higher or lower than normal, but the difference between the average temperatures remains at least 0.4 ° C, in this case there are no pathologies and deviations in health. This manifests the individual characteristic of the body.
Although the method for measuring BT is simple and affordable for determining pregnancy or diagnosing health, it should not be the only factor for diagnosis. Therefore, it must be combined with other methods. For example, to determine ovulation, you can additionally use test strips or ultrasound monitoring, to confirm pregnancy - blood donation for hCG or a test, and to diagnose abnormalities in health, take laboratory test data into account.
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