ovulation and basal temperature

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Ovulation is the release of a mature egg from the ovary. Ovulation usually occurs once a month on about day 14 of a normal 28 day cycle. Since normal ovulation is essential to female fertility it is usually checked early in infertility investigations. You can assess your own ovulation by keeping a basal temperature chart as described below.

If we observed a normal fertile ovary each month, we would see that several follicles - each containing a single egg - are growing in size in each cycle. However one follicle becomes larger than the others (dominant) and will be the one that ovulates. Occasionally more than one follicle ovulates and this can lead to fraternal twinning or multiple births. The fertile follicle has the capacity to produce hormones as well as just growing the egg. At ovulation, the mature ovum (egg) is released and the remaining cells that previously surrounded the egg, now become a hormone factory (corpus luteum) and the hormones support the early pregnancy.

Measuring basal temperature

Basal temperature is the minimum temperature in the day and usually occurs at about 6 am. It is best if you can measure your basal temperature but it is more important that you are consistent and measure at the same time each day. Have your thermometer next to your bed overnight and take your temperature in the morning before you move around. Record it immediately. Oral temperature is influenced by drinking or sleeping with your mouth open. Vaginal temperature is a little higher but is generally far more consistent. Download your free basal temperature chart and the instructions for completing your basal temperature chart.

Interpreting basal temperature

The basal temperature before ovulation should be about 36.4 degrees C. There should be a dip of about 0.2 degrees on the day before ovulation (which coincides with a surge in oestrogen) and then the temperature should rise to 37 degrees C within two to three days. Minor variations to this pattern are still consistent with normal ovulation but serious variations indicate a problems. If your chart isn't normal you can interpret the likely cause from the very inexpensive temperature chart e-book. This little book shows examples of normal and abnormal cycles and explains the differences between them.

How can you overcome problems in your temperature chart?

The most common problems in charts are (a) temperature is too low before ovulation, (b) temperature does not reach 37 degrees after ovulation or does so too slowly, (c) temperature does not change. Some simple solutions to these problems are given in the temperature chart e-book but a more detailed explanation of these and most other problems can be found in It Takes Two. The on-line lifestyle evaluation, with or without email or telephone counselling, is likely to identify the source of the problem and provide a relatively simple solution.

Baby Josh (above) was conceived naturally after his mother optimized her ovulation after reading It Takes Two.



Adelaide, South Australia, Phone (international: +618 8244 7551 - Australian central time)

Helpful Links


Our other sites of interest:

Whole of Life Drug-free Preventative Health: Information, Services & Products
Ez-fertility Evaluation: A comprehensive Evaluation and Personal Report for couples who are planning pregnancy and wish to avoid problems


Site updated January 2009