FX for you poppiebug.

going to put you on to be determined then.
Mrsmummy2 - got the following from FF explaining the hormones that affects the temps.
"Info Tidbit
What is the role of progesterone?
After ovulation, the corpus luteum (the remains of the follicle that released an ovum at ovulation) produces the heat-inducing hormone, progesterone.
The principal reproductive function of progesterone in the luteal phase is to cause changes that prepare the lining of the uterus for the implantation of a fertilized ovum.
Progesterone also causes the resting body temperature to rise after ovulation. Because progesterone is only secreted in high levels after ovulation, it is possible to identify ovulation for the day BEFORE the temperature rises when temperatures are plotted on a graph.
To illustrate, see the image below. The blue dots represent daily temperature readings. Ovulation is identified by the vertical red line. The horizontal red line is a "coverline" to help to visualize the biphasic pattern.
Low temperatures are observed before ovulation and higher temperatures are recorded after ovulation.
Your BBT, or basal body temperature, is your body temperature at rest as measured in the morning after at least three hours of sleep, before you get up, with a special BBT thermometer that you can buy at your drugstore.
Before ovulation, during your follicular phase, basal temperatures are relatively low. After ovulation, your basal body temperature rises sufficiently that you can see the difference between your pre-ovulation and post-ovulation temperatures when they are plotted on a graph.
A fertility chart that shows ovulation detected by BBT will have a BIPHASIC pattern. This means that it will show lower temperatures before ovulation, a rise (thermal shift), and then higher temperatures after ovulation. Ovulation usually occurs on the last day of lower temperatures. Your BBT corresponds to the heat-inducing hormone progesterone. This is the only sign that that you can observe on your own that can confirm that ovulation actually happened. All the other signs only tell you that ovulation may be approaching.
Your temperature sign is the sign that will best help you to precisely pinpoint the day that ovulation occurred. This is because progesterone, and hence your temperature, increase quite dramatically just after ovulation has taken place."