FERTILITY SIGNS - Basal body temperature

   The first fertility sign that we have to discuss is the basal body temperature (BBT) or waking temperature.
   Probably all of you have already learnt in biology class that the normal body temperature of humans is between 36-37 degree Celsius. This, however, keeps changing during the day according to our activity, obviously while we are working out it will be higher, while we are at rest it will be lower. The waking temperature can be taken in the morning when we wake up after at least 3 hours of consecutive sleep. This is the time of the day when it is the lowest. As soon as we get out of bed and start our daily activities it will rise, but we are not talking about big differences, only few tenth or hundredth degree changes.
   The fact that the basal body temperature changes during the menstrual cycle, in the first half it stays in a lower range, in the second half it rises to a higher range was first discovered in 1868 by Dr W.Squires, but he could not figure out the reason behind it.
   Van de Velde was the one who realized the connection between the mid-cycle temperature shift and ovulation in 1904. In 1928 he also figured out that the reason for the higher temperatures is the progesterone hormone produced by the corpus luteum after ovulation. However the field studies and researches took place decades later by Dr John Marshall British neurologist who published the proof of this theory in 1968.
   But why is this an important part of Fertility Awareness? Because the woman who takes her BBT daily and notes it in a chart will be able to differentiate between the pre-ovulatory (follicular) low temperatures and the post-ovulatory (luteal) high temperatures. This will tell her if ovulation happened and she can also estimate its day. It can happen that ovulation does not occur for some reason but the temperature chart will show this, the temperatures will remain low throughout the cycle. Also whoever is trying to conceive can save money on pregnancy tests because the production of progesterone hormone is continuous while expecting a baby, the temperatures will stay high for 9 months.
   The only problem with the basal body temperature is that it is very sensitive, there are numerous factors that can throw it off balance and cause a false reading (bad sleep, consuming alcohol, illness, travelling etc.) If you join a course and learn the Fertility Awareness Method though, you will be able to identify these factors and know what to do about them. Also I have to tell you that the BBT is not taken in the armpits because that place is unreliable when we are talking about so small changes. It has to be taken in the mouth under the tongue, in the vagina or in the rectum (always the same place). There are basal body thermometers available that were developed specially for this cause and show hundredths of degrees compared to the general thermometer that was designed to indicate fever and shows only tenths.
   As I have said it is very useful to chart your waking temperatures but it will tell you only when your fertile phase ends since it rises 1-2 days after ovulation.

   In the next post we will see which sign shows us the onset of fertility and determines the length of the fertile window in the cycle. Stay with me! 😉