The norm of basal temperature during pregnancy: chart

The menstrual cycle in the fair sex, which lasts an average of 28-35 days, can be divided into 2 phases: pre- and post-ovulation. In the first phase of the sexual cycle in a healthy woman, there are usually no alarming fluctuations in temperature. In her ovaries, under the influence of estrogens, eggs gradually mature (usually 1 per month), which is not accompanied by a rise in temperature. On the contrary, in the initial days of menstruation, there may be some decrease in it, but during the entire first phase, fluctuations in basal temperature remain within 36.1 - 36.8 degrees. If it gets higher, this indicates either inflammation in the reproductive system, or a deficiency of estrogens, which, as we know, lower the body temperature.

If you follow the graph of basal temperature during the first phase of the female cycle when planning pregnancy, you can see how it gradually decreases during the first week, which indicates an increase in the production of estrogens necessary for the maturation of the egg, and a decrease in progesterone synthesis. To some, this moment may seem insignificant, because pregnancy is judged by the second phase of the cycle, which is paid more attention to. In fact, by changes in the temperature of the first phase, one can already judge the functioning of the endocrine system and, in particular, the gonads. With a lack of estrogen (temperature above 36.8 degrees), the egg may simply not mature, and it is useless to wait for pregnancy in this case, although the problem is usually solved by simply introducing female hormone substitutes.

When the egg is ripe and ready to be released, the day before ovulation or on the same day, the woman's body temperature drops noticeably to 36 - 36.2 degrees (the reason lies all in the same estrogens that are released in the maximum amount during this period ). After the egg leaves the follicle, the need for increased estrogen production is reduced, but there is a need to maintain a possible pregnancy. In place of the ruptured follicle, a corpus luteum appears, and the synthesis of progesterone begins, which at this stage is more important for maintaining a possible pregnancy. This causes a consistent increase in body tissue temperature during the second phase of the menstrual cycle up to the 21st-25th day, after which it either falls (if conception has not occurred) or remains elevated and further (when pregnancy occurs). [1]

There is no need to be afraid of the rise in basal temperature in the second phase when planning a pregnancy. This is a normal physiologically determined process, and the temperature difference is not so high. The interval between the highest temperature of the 1st phase of the cycle and the maximum thermometer in the second is usually 0.4-0.5 degrees.

The preovulatory drop in temperature after the rupture of the follicle is accompanied by a sharp increase (the fact is that before the corpus luteum appears, progesterone is synthesized and accumulated in the follicle, and after its rupture it is released into the blood, which causes a sharp jump in temperature, although on the first day it rarely rises to 37 degrees). It is this temperature jump in the middle of the cycle that women who want to get pregnant should pay attention to, because it is he who indicates ovulation and the optimal opportunity to become a mother.

Later, thanks to the luteinizing hormone that enters the bloodstream on the eve of ovulation, a corpus luteum is formed, which, as it develops, increases the concentration of progesterone in the blood, which means that the temperature continues to rise, reaching values of 37.1 - 37.2 degrees (sometimes up to 37, 7, which is not considered pathological if not kept for too long).

After the 21st day of the cycle, in the absence of the fusion of the egg and sperm, the iron, called the corpus luteum for its color, becomes unnecessary, it gradually atrophies and is excreted from the body during menstruation. During this period, there is a gradual decrease in the production of progesterone and, accordingly, a decrease in body temperature even before the onset of phase 1 of the next menstrual cycle.

If conception has occurred, the gland is actively functioning for another 2.5-3 months, and sometimes longer, thereby preventing pregnancy failure. Ask the doctors a question about what the basal temperature should be during pregnancy, and they will not answer specifically, because a temperature of 37.1 degrees is also considered normal, and a couple of tenths of a degree more - 37.2-37.4.

In many ways, these indicators depend on the individual characteristics of the body of the expectant mother, the activity of the processes occurring in it, because even in the absence of hormonal changes associated with pregnancy, the body temperature of different people at rest can differ by 0.1-1 degrees. It is not surprising that individual temperatures can be set for potential mothers, and if it does not deviate from the norm by more than 0.8-1 degrees, there is no reason for concern.

If the basal temperature after the conception of a child does not slightly coincide with the norm (the generally accepted norm is a temperature of 37.1-37.3 degrees), you should not worry in vain, because the individual norm can only be determined in comparison with the usual temperature. For example, if in phase 1 of the cycle a woman’s temperature did not rise above 36.5 degrees, then in phase 2 it is unlikely to be above 37.

It should be noted that it makes sense to talk about what the basal temperature should be during pregnancy in the morning after waking up, it is not logical to measure it in the evening, because the body spends energy per day, is influenced by internal and external factors, so the measurement results will not be adequate. Advice to measure basal temperature during pregnancy twice a day has no logical basis. Evening measurements will differ both from the morning ones and from each other, regardless of how the pregnancy proceeds. [2]

Basal temperature and pregnancy

The measurement of basal temperature is considered an affordable and quite effective method for diagnosing pregnancy, which allows you to detect it from the very first days without additional instrumental and laboratory studies. Usually, a woman learns about the onset of pregnancy by the absence of menstruation at the appointed time and a few days after the planned start.

Basal temperature with its regular measurement allows you to find out about pregnancy even before the delay. Indeed, most often the interval between conception and the beginning of the next menstruation is about 14-16 days, during which the egg has time to go through several divisions, change its place of residence and gain a foothold in the uterus. During this period, the nervous system and some organs are formed in the unborn child, even if he does not look much like a person, but he will definitely become one with the help of his mother.

Until a placenta is formed around the embryo, which subsequently becomes an embryo, the corpus luteum will be responsible for its preservation, producing progesterone in sufficient quantities. On the eve of implantation, this hormone prepares the uterus for the introduction of a fertilized egg, then restrains its excessive activity and premature contractions, prevents the rejection of the embryo as a result of incorrect work of the main defender of the body - the immune system, which considered it a foreign body. Progesterone also contributes to the production of other hormones that are considered important for the normal development of the fetus. Maintaining pregnancy and preventing premature birth. [3]

It is not surprising that during pregnancy, the basal temperature has higher values both during the onset of pregnancy and in its early stages. How to understand that the conception went well, and there is no need to worry about the level of progesterone? Again, according to body temperature at rest. Its values during the first month should correspond to those that were established within a week after the day of ovulation. This temperature usually lasts until the period of placentation (the end of the 2nd month of pregnancy), and then gradually returns to normal. Although in most cases it remains somewhat elevated (within 37 degrees), because the secretion of progesterone in the body of a pregnant woman continues, but this function is already performed by the placenta after 12-14 weeks from the onset of conception.

The onset of placental secretion of progesterone again causes an increase in its level in the woman's body, because the larger the child becomes, the more difficult it is to restrain the activity of the uterus. But the body of the expectant mother no longer reacts so sharply to changes in the hormonal background. He develops a certain resistance to progesterone surges, so a noticeable increase in temperature is not observed until the end of pregnancy, although the concentration of the hormone during all this time increases by 8-10 times. It decreases sharply only before childbirth, which allows the uterus to actively contract. [4]

Basal body temperature chart

Speaking about the norm of basal temperature during pregnancy, we noted that not all deviations from the generally accepted norm are considered pathologies. Body temperature is an individual matter. Progesterone can change it slightly, starting from stable readings for each individual person.

It is not difficult to determine your normal basal temperature by measuring it daily after sleep in the middle of the first phase of the cycle. You need to be prepared for the fact that even in a relatively calm time, when the follicles mature with the participation of follicular progesterone and estrogens, there will be fluctuations in the thermometer readings, which is an indicator of the stability of estrogen production. Such fluctuations within 0.5 degrees are quite normal, but what should we start from when calculating the rate of basal temperature?

We take the average indicator as a starting point, which will reflect our true norm, or the maximum and minimum indicators, by which we can immediately determine both the lower and upper limits of the norm.

In principle, whether to draw up a schedule of basal temperature when planning a pregnancy for days, weeks, months, or simply keep a diary, recording the results of regular measurements in it, is an individual matter. But such records and graphs help to track the dynamics of temperature indicators, calculate the moment of its maximum drop, followed by a sharp increase in values, which indicates ovulation and a good opportunity to conceive a child, to effectively protect yourself if the birth of a child is not yet included in the plans of a woman and her partner. Not surprisingly, for diagnostic purposes, doctors still insist on drawing up a graph (temperature curve), which is later easier to decipher due to the clarity of the results and their changes. [5]

Gynecologists distinguish these types of temperature curves, which can be used to judge the presence of various disorders in the reproductive system and hormonal abnormalities:

• The norm for a two-phase menstrual cycle is the difference in basal temperature in the 1st and 2nd phases of the cycle of 0.4 degrees. At the same time, doctors compare the readings of the thermometer at the time of the temperature drop before menstruation and before ovulation. In the post-ovulation period, there is a jump in temperature, after which its values are kept at a relatively high level for 12-14 days.
• If the rise in temperature in the second phase is less pronounced (0.2-0.3 degree interval), i.e. Temperature fluctuations are insignificant, this may indicate a lack of production of sex hormones: estrogen and progesterone. The low rate of temperature rise after ovulation indicates that the follicle has not ruptured; there was no ovulation, the egg in it did not ripen.
• When the rise in temperature is observed shortly before the onset of menstruation, i.e. At the end of the 2nd phase of the cycle and does not fall on the eve of menstruation, while the second phase of the cycle is unusually short (less than 10 days), we can still talk about the same two-phase cycle, but with the insufficiency of the second phase (luteal). In other words, we are talking about violations of the formation and functioning of the corpus luteum, i.e. Progesterone deficiency, as a result of which a fertilized egg is not able to properly establish itself in the uterus. This causes spontaneous miscarriages in the very early stages of pregnancy.
•  If the temperature curve shows no temperature difference in the two phases of the cycle (monotone curve), i.e. There are no noticeable temperature fluctuations in the middle of the menstrual cycle, they speak of an anovulatory (single-phase) cycle. In such women, menstrual bleeding can occur regularly, which is perceived as the absence of any pathology. In principle, this is true when it comes to teenage girls during the formation of menstruation, pregnant women and nursing mothers.

There are unusual cycles without the maturation and release of the egg in mature healthy women due to stress, strict diets, lack of sleep, intoxication, some somatic diseases, hormonal changes (menopause). Pathology is considered if such cycles become regular.

Menstrual cycles without ovulation, taking on a systematic character, can cause infertility. They arise as a result of a violation of the production of female and male hormones in a woman's body, genetic mutations, polycystic ovaries, and a violation of their functionality of some other pathologies of the reproductive system.

Symptoms of an anovulatory cycle can be delays, shifts, lack of menstruation, excessive bleeding during menstruation, etc. This allows you to suspect a pathology and consult a doctor in time. True, in some cases, changes in the time and nature of menstruation are not observed, and a woman may suspect violations only on the basis of repeated fruitless attempts to become pregnant. Determine if ovulation is occurring, i.e. The maturation and release of the egg from the follicle, without which the conception of a new life is impossible, is possible using a graph that shows changes in basal temperature during the cycle, and preferably over several cycles. [6]

• In some women, the temperature curve is so individual that it does not fit into any of the above types. Most often, these are erratic changes and jumps in temperature throughout the entire menstrual cycle. Unlike a single-phase cycle, on the graph you can see a pre-ovulation drop and the temperature jump following it in the middle of the cycle, and in other periods the temperature can fluctuate noticeably by day.

In such a situation, the doctor may suspect estrogen deficiency, as a result of which there is no temperature balance. In the second phase of the cycle, such women may experience temperature jumps above normal, i.e. Up to 37.6-38 degrees in the absence of pathologies of an infectious and inflammatory nature.

Charting a basal temperature during pregnancy or planning it is a responsible matter. For clarity, after plotting points on a graph, one axis of which reflects temperature changes with an interval of 0.1 degrees, and the second one counts the days of the menstrual cycle in increments of 1 day, you need to draw 2 lines: the middle (horizontal) and the ovulation line (vertical). We draw the middle line in this way: we discard the readings of the first 5 days of the cycle and draw a line according to the matching temperature readings of the next 6 days. We draw the ovulation line, retreating a couple of cells to the right of the pre-ovulation temperature drop.

This is all easy to do on a normal schedule, when the onset of ovulation is easy to predict (the middle of the cycle, if its duration is known), and we are talking about measuring temperature when planning a pregnancy or to increase the effectiveness of contraception. The hormonal disorders present in the body tend to change the temperature curve, which makes it difficult to interpret and requires consultation with a specialist.