Charting your temperature is one way to keep track of your luteal phase and when you're at your most fertile.
Knowing the length of your luteal phase allows you to more accurately predict at what point in your cycle ovulation occurs.
This is important information when you’re trying to conceive, because you're at your most fertile for only a short window of time each month: two to three days before you ovulate, and for about 12 to 24 hours after ovulation.
The luteal phase is the second half of your menstrual cycle, when fertilisation and implantation may occur. This phase starts straight after ovulation and ends when your period begins.
Your body temperature increases to create the optimum environment for pregnancy at this time.
Typically, the duration of the luteal phase lasts between 10 and 16 days, and is generally consistent from cycle to cycle, averaging around 14 days for most women. We've used this average as the default luteal phase length in the Essential Baby Ovulation Calculator.
If you'd like to find out how long your luteal phase actually is, use our Basal Temperature Chart to make a daily record of your body temperature, to help you work out your luteal phase length and predict the day of ovulation.