By charting your fertility signs you can detect when you are most fertile, when ovulation may be occurring and when it has occurred. An increase in estrogen levels can infer ovulation is approaching and signs of this include the presence of thin, watery and stretchy cervical discharge. Ovulation prediction kits (OPKs) and other fertility monitors (e.g. the clear blue fertility monitor – see my review here), can tell us that ovulation is about to take place. They do this by measuring the levels of Lutineizing hormone which increases dramatically 12-24 hours before ovulation. By charting your BBT you can pinpoint the day of ovulation. Your body temperature will rise due to an increase in the hormone progesterone following ovulation.
Reading your chart.
A perfect chart will show all your fertile signs and OPK results line up with the predicted ovulation day on your chart. When your chart is perfectly lined up it is easy to interpret. For several days leading up to ovulation you should have recorded watery discharge or EWCM. The day before (and sometimes the day of) ovulation you should have a positive OPK if you use them. The day after ovulation you should see your temperature shift on your chart and following 3 days of higher temperatures your ovulation day can be confirmed – usually on phone apps this is indicated as a vertical line. Until you have 3 days of higher temperatures assume you are still fertile. Once ovulation has taken place your cervical mucus should change to the creamy, tacky infertile type.
Unfortunately, chart patterns are not always perfectly clear. If you are in any doubt that ovulation has taken place e.g. maybe your temperature has risen but your cervical mucus was creamy or your OPKS were negative, and you are trying to conceive then carry on having intercourse every other day until you are sure. If you need any help with your charts please feel free to email me a screen shot at email@example.com and I will be happy to take a look for you.
Common issues you may come across:
Slow or Sloping Rise
Following ovulation your temperatures may be slow to increase giving a gentle curve rather than an abrupt shift. It is common for this to occur for several days after ovulation as progesterone levels start to rise following ovulation.
A Fallback Rise
This pattern is unusual but shows a distinct BBT rise after ovulation followed by a drop in BBT before the rise returns and is maintained. This can cause confusion on charts and make you question when ovulation has taken place. This is when your other fertile signs come into place to help you pinpoint when ovulation has taken place.
This is when your BBT increases in a sort of zig zag pattern and is very common. BBt rises and drops each day but the overall pattern is an increase.
This pattern shows a rise which will remain steady for a day or two then another rise and so on until your peak BBT is reached. The chart ends up looking like it is increasing in steps.
This is a pattern that I am very familiar with having experienced very long cycles in the past. You may see several patches of fertile cervical mucus and several positive OPKs before you finally ovulate. You may even get the odd high temperature here and there which will make you question if ovulation has taken place. Ovulating late in your cycle can occur from time to time as a one off but if you are trying to conceive and it is a common occurrence it can become very frustrating and stressful. If you are concerned about long cycles then go and speak to your GP.
Often erratic BBT can be down to the way you are taking your temperature. If you record your BBT orally and you are consistently getting erratic BBT recordings (up and down each day) then it may be useful to try temping vaginally. Remember to take care when inserting the thermometer and to wash it thoroughly after each use.
Temperatures out of place
You may see the odd temperature here and there that does not fit in with your chart e.g. a high BBT during before ovulation or a low BBT after ovulation. As it is more the overall pattern that is important when charting and not the individual BBT that we are interested in you may disregard these temperatures.
High BBT during your period
It is normal to have BBT that are higher during your period as your lining is shed and progesterone levels decrease. Once your period is finished your BBT will drop to your normal pre ovulation temperatures.
A sudden drop in BBT may occur the day before or day of ovulation which may be due to a rise in estrogen levels (which is a cooling hormone) before ovulation. This dip will be followed by a rise in BBT following ovulation.
Numerous patches of fertile cervical mucus
Often you may get several patches of fertile cervical discharge before you ovulate especially if your cycles are very long. Each patch of fertile mucus may indicate you are within your fertile window so if you are trying to conceive then have intercourse whenever you experience this until you get your thermal shift.
Several positive OPKs
Luteinizing Hormone (LH), is detected by OPKs and this hormone may rise several days before you are about to ovulate (although usually it peaks 12-24hrs before). This is why you should not solely rely on OPKs to indicate ovulation has occurred. Only a shift in BBT can confirm this. When you get a positive OPK assume you are about to ovulate and have intercourse until you see your BBT rise for 3 consecutive days. Woman with Endometriosis and other fertility issues may get false positive OPKs often. You may also get positive OPKs during an anovulatory cycle (a cycle when you do not ovulate). Some fertility treatments (drugs) may also affect the readings on OPKs giving false positives.
A lack of fertile cervical mucus during the fertile window.
If you do not get much fertile cervical mucus around the time of ovulation then it may affect your fertility. If this is a common occurrence then take a look at my sections on ‘How to increase your cervical mucus naturally’ and ‘sperm friendly lubricants’.
Fertile cervical mucus after ovulation.
Usually the fertile type of cervical mucus will be replaced by the creamy, tacky, non fertile type following ovulation. If you still see some fertile mucus during your luteal phase then it is nothing to be concerned about. As long as ovulation has been clearly confirmed on your chart you can be sure you are no longer fertile. If, however your chart is unclear you may not have ovulated yet and should treat yourself as still fertile.
Temperature shift may be ambiguous
If you have a chart that is unclear then you need to remember that the key thing is that you have intercourse at the correct time during your fertile window. If you are unsure when you have ovulated then take the last possible option on your chart to ensure you do not test too early.