Charting basics - recognising your fertile phase

Well, thankfully there are clear clues. With each cycle your body experiences physical changes that indicate that ovulation is imminent or has already occurred such as: a shift in temperature, changes in the amount and consistency of cervical mucus and the position of the cervix. If you keep track of a combination of these changes you'll understand your cycle better and will be aware when ovulation is delayed for some reason, as sometimes happens. Taken together as a group, tracking these changes is referred to as the fertility awareness method, or FAM, not to be confused with the unreliable rhythm method.

The three main fertility indicators are:

Waking temperature
Cervical mucus, or fluid
Cervical position

Waking temperature
With each ovulatory cycle your waking (basal body) temperature dips slightly just before ovulation and then rises, indicating that ovulation has taken place - usually the day before the sustained rise. If you track the changes in your waking temperature over the course of a few months you'll be able to see a difference between the lower, preovulatory temperature range, and the higher, postovulatory range. While you might not be able to discern a dip before ovulation, if you look at the temperature ranges you should see a pattern of low and then higher temperatures. Because the lengths of cycles can vary, tracking temperature on its own won't allow you to reliably predict ovulation, although you can have fun making increasingly educated guesses, but it will tell you when ovulation has taken place, so you'll know when your fertile phase is over.

As the second part, or luteal phase, of your cycle after ovulation doesn't usually vary more than a couple of days in length, once you're sure ovulation has taken place you'll know when you should expect your period. So, if you experience delayed ovulation due to stress or some other factor, you'll know how late your period is going to be and won't be tricked into thinking you might be pregnant when there's a delay.

Taking your temperature
When charting your waking temperature it's important that you take the temperature at the same time every day (or note the different time on your chart so you can take it into account) and before you get out of bed or exert yourself physically (we'll allow reaching over to pick up the thermometer, but that's about it). You'll need a thermometer sensitive to changes of one-tenth of a degree (usually sold as basal body temperature thermometers).

You'll also need to note any unusual circumstances as your waking temperature can be influenced by factors such as running a fever, drinking alcohol and heavy exercise the day before. You can take your temperature either orally, vaginally or anally, but you need to be consistent throughout the cycle.

To record your temperatures you can download one of our temperature charts as a Word document, Excell file or image.

Cervical mucus, or the Billings Method
The qualities and quantities of your cervical mucus, or fluid, change throughout your cycle and by tracking the pattern of these changes you can learn to anticipate when ovulation is likely to be imminent.

Leading up to ovulation your cervical mucus changes consistency to provide a healthy environment for sperm during your fertile time around ovulation. Most women's cervical mucus changes from a sticky or gluey texture, usually cloudy, white or yellowish in colour, to a milky or lotion-like wet consistency and finally to the clear, slippery and stretchy consistency similar to raw egg white that makes the most favourable environment for sperm.

The days of egg white cervical mucus, there may be several, are the days when you are most fertile. Fertility wanes when the mucus reverts to being sticky, cloudy or dry. You might also have wet cervical mucus in the days immediately before your period starts, but this doesn't indicate a fertile time.

You can check the consistency of your cervical mucus when you go to the bathroom by collecting some mucus or fluid on either tissue paper or your fingers from your vaginal opening. It's easiest to test the consistency of the fluid between two fingers. You should check the cervical mucus several times a day and note the results down on your chart.

Also important is the actual feeling you get in your vagina, once you start thinking about it you should notice that at certain times the inside of your vagina feels wet, cold or sticky and at other times you feel no particular sensation at all. These vaginal sensations should follow a similar pattern and you might still feel a wet sensation after your last day of noticeable egg white or wet cervical mucus, which indicates that you are still fertile.

Cervical position and changes
Your cervix also changes during your cycle to become more receptive to sperm during your fertile phase. Usually your cervix is firm and closed but leading up to ovulation it rises and becomes soft, open and well lubricated to allow sperm to pass through more easily.

If you want a third indicator of your fertility besides temperature and cervical fluid, you can check your cervix yourself by inserting a clean, well-trimmed finger into your vagina and feeling the cervix, starting the first day after the end of your period. It will probably take some time before you're able to clearly distinguish the different states and positions of your cervix.

For some women this is a step of complication too far, but others may find it a useful third indicator that takes up little time once they are in the habit of daily checking.

Other signs of ovulation
Some women are very aware of when they are ovulating as they have learnt to read other subtle physical changes and sensations. You may experience any or none of the following signs of ovulation.

• Pain, cramping or aching near the ovaries known as 'mittelschmerz'
• Water retention or bloating
• An increased interest in sex
• Sensitive or sore breasts
• Spotting of blood
• Changes in mood

If you track these signs along with the main fertility indicators you may well see patterns emerging and begin to make sense of previously unexplained aches, pains or mood swings.

Further reading
If you plan to use charting for contraception you should invest in a book on FAM for a guide to all the rules on when you are fertile. When you are trying to conceive, it may be enough to simply be aware of when you are most fertile, but it's still a good idea to read a dedicated book on the subject. ThinkBaby particularly recommends Toni Weschler's 'Taking Charge of your Fertility'. Available in bookshops and online.