Knowledge Sharing

2015.09.16

How to measure? How to detect ovulation?

⋙ What is basal body temperature?
What is basal body temperature (BBT) is the lowest body temperature attained during rest after 6 to 8 hours of sleep. It is the lowest body temperature a day. Typically, a women have lower temperature before ovulation and causes a slightly increase of 0.3 to 0.6℃after ovulation. The rise in temperatures can return to normal by next menstruation period.

⋙ Is the basal thermometer the same as the regular thermometer?
The basal thermometer, a thermometer that measures the menstrual cycle, is completely different from a regular thermometer.
  1. A basal thermometer shows you the temperature in tenths of a degree that allows you to measure the slight changes.
     
  2. The decimal point is generally not easy to read and difficult to record. "The basal thermometer measuring the menstrual cycle" uses a 0V scale, which is better for recording.
     
Basal thermometers are available to buy in the pharmacies, or ask your doctor.
The basal body temperature measured in the morning after sleeping (it doesn't matter even if you sleep until noon) before any physical activity, even talking, exercise, eating or emotional interference. Take the temperature under the tongue at last 2 minutes using the basal thermometer which places on a bedside table or under the pillow last night. Then record the temperature on the basal body temperature chart.

Am I ovulating?
It mainly observes the pattern of temperature highs and lows, and its duration.

Typically, the ovary produces progesterone, which causes a childbearing-age woman’s temperature to increase after ovulation as high as 36.8 to 37℃. It is higher between 0.3~0.5℃ before ovulation, but falls on day 1 to day 2 before period, or on first day in period.

Therefore, the curve of daily basal body temperatures during the normal ovulation menstrual cycle is a biphasic curve (the temperature changes of biphasic patterns from high to low is shown in the figure as below: "normal basal body temperature curve").
 
基礎體溫曲線

The anovulatory menstrual cycle, due to the lack of progestin.
基礎體溫曲線-無排卵

The basal body temperature of childbearing-age women is the same as the menstrual cycle, which changes periodically related to ovulation. The first day of menstruation is considered on Day 1 of the cycle. The regular cycles are individual from 21 to 35 days, with an average of about 28 days. It is divided into the follicular phase before ovulation and the luteal phase after ovulation. The duration of the follicular phase is not certain, but the luteal phase is between 12 and 14 days long. The next day after ovulation, the corpus luteum is formed to produce progesterone, which increases the body temperature by about 0.6 degrees Celsius, causing temperature difference. The duration of high temperature lasts about 12-16 days (average 14 days).
 
  1. If there is no pregnancy, the corpus luteum atrophy to stop secreting progesterone, the body temperature drops and returns to the basic line, then menstrual comes.
     
  2. If you are pregnant, hormones secreted from the embryo make the luteum is kept secreting to maintain the body temperature high.
     
  3. Dysfunctional ovaries make no ovulation and luteum formation, and keeps low temperature.