Basal temperature when your period is delayed

By measuring a woman's basal body temperature, the ovulation period of her cycle is determined - the time of the most probable fertilization. What is the basal temperature when the period is delayed and why?

Basal temperature during early pregnancy and delayed periods

Basal temperature is the body temperature measured in the oral cavity or rectally in the morning - without getting out of bed, that is, while the body is at rest. Therefore, basal temperature is not measured during the day and in the evening if your period is late. Why?

Because at night the human body temperature decreases, and when it is measured immediately after waking up, factors that can somehow influence thermoregulation are excluded, in particular: food intake, physical activity, stress, weather, water procedures and much more.

For more information on how to measure basal temperature when your period is late and how to correctly plot a basal temperature chart during pregnancy before your period is late, read the publication – What is basal temperature and how to measure it

During the first 14 days, the cycle is regulated by estrogens, and before ovulation - that is, before the egg leaves the mature follicle and enters the uterine (fallopian tube), where it can be fertilized - the basal temperature is usually between +36.1 and +36.4 ° C, although these figures have individual variations.

An increase in basal temperature by 0.2-0.6° is one of the signs of ovulation, during which its values can reach + 36.6-37.3°C. What is this connected with? The only reason is an increase in the level of progesterone in the woman’s blood – a hormone produced by the corpus luteum of the ovaries. It is assumed that the thermogenic effect of progesterone is mediated through the hypothalamus thermoregulation center. [ 1 ]

About a day after ovulation, progesterone levels rise sharply (from 1-1.5 to 3-4 ng/ml) and continue to rise until they peak (10-20 ng/ml) a week after ovulation – to support the implantation of the fertilized egg in the uterus, and also to help maintain the pregnancy by preventing menstruation. Full details – Progesterone during pregnancy [ 2 ]

There may be two options. If the basal temperature does not decrease, this may indicate that the progesterone level remains high due to the onset of pregnancy. In this case, menstruation does not occur on time (that is, the woman notes a delay in menstruation), and the temperature readings will remain high throughout gestation. What should the basal temperature be during early pregnancy? Within +36.6-37.4 ° C, but again, there may be individual nuances. You can learn about them from the publication - Basal temperature during early pregnancy

It is not difficult to guess what the basal temperature is during pregnancy before a missed period. When conception has occurred, then during these two weeks before the missed period, the basal body temperature can fluctuate from the same +36.6 to +37.4 ° C. Useful information is also in the material - All about the first weeks of pregnancy

The second option: if the basal temperature readings decrease, it means that the progesterone level decreases, that is, fertilization has not occurred, and the endometrium prepared for it is destroyed, which leads to the onset of menstruation. [ 3 ]

Delayed periods with low basal temperature

If a woman's thermometer does not rise above +36.5℃ even during the high temperature phase (when ovulation should occur), this means that her basal body temperature is low.

Of course, a delay in menstruation with a low basal temperature is not excluded. The main reasons for their delay - menstrual cycle disorders - are general fatigue, lack of sleep, stress, insufficient body weight, obesity, excessive physical activity, insulin resistance, endocrine problems (with the pancreas or thyroid gland), hormonal contraception, the onset of menopause (which in some women can begin before 40-45 years). [ 4 ]

Also to consider is the possibility of anovulation – the absence of ovulation, when the egg is not released and the hormones do not enter the luteal phase. Anovulation is essentially a prolonged follicular phase. And it can occur with amenorrhea – the absence of menstrual bleeding unrelated to pregnancy and indicative of health problems and hormonal imbalances.

High basal temperature in the absence of pregnancy

In many cases, women may complain that their basal temperature is 36.9-37.3, but the pregnancy test is negative.

Firstly, there are many good reasons not to place great hopes on an early pregnancy test, since all existing tests are based on the detection of the hormone hCG – human chorionic gonadotropin (synthesized by the chorionic cells of the implanted egg, which is transformed into an embryo) rather than progesterone. [ 5 ]

Secondly, even when progesterone levels are slightly higher, this does not mean that fertilization has taken place and the woman is pregnant. Sometimes there will be a few days with higher temperatures due to residual progesterone levels from the last cycle, but they will drop again as soon as the period begins. [ 6 ]

A prolonged increase in basal temperature may be associated with:

• with hyperthyroidism, in which there is an increase in the production of thyroid hormones (which increase the rate of cellular metabolism);
• with prolonged overnutrition;
• with polycystic ovary syndrome (due to the action of vasoactive endothelial growth factor peptides - VEGF, released from ovarian cyst cells.
• with the presence of malignant neoplasms, the cells of which have a high level of metabolic activity;
• with iatrogenic complications of ovarian stimulation with hCG analogues during IVF procedures (ovarian hyperstimulation syndrome). [ 7 ]

It is important to keep in mind that daily temperature fluctuations within a few tenths of a degree depend on the phase of the menstrual cycle. [ 8 ] Thus, the temperature during the entire luteal phase of the cycle will be higher than in the follicular phase. When the luteal phase begins with ovulation, the temperature rises and remains high for 12-16 days (one day with a high temperature does not indicate ovulation). When the follicular phase begins with menstruation, the temperature will fall and remain low.