The luteal phase is the second phase of your cycle – it starts after ovulation and ends when your next period begins.
After ovulation, the follicle that released the egg (called corpus luteum) produces progesterone which the body needs to soften the lining of the uterus. This makes it easier for the egg to attach if fertilized.
An increase in progesterone levels in the body also increases the temperature, which is what the Natural Cycles algorithm uses to both confirm that you have ovulated and estimate when you ovulated.
If the egg is not fertilized, the corpus luteum stops producing progesterone after approximately 12-16 days, which causes your temperature to drop again, and your period will start soon after.
How long does the luteal phase last?
The luteal phase lasts roughly between 10-16 days – the average length is 14 days. Because the length of the luteal phase usually remains rather stable for each user from cycle to cycle (although it varies from person to person), your specific average luteal phase length can give more information about the timing of ovulation.
On your Cycle Insights page (accessible via the Today view > See cycle insights), you can see detailed information about your luteal phase, such as how long it usually lasts.
What about PMS?
Towards the end of the luteal phase, you may experience PMS symptoms. This may be a response from your body to the hormonal changes that occur during this phase (learn more about PMS here).
The symptoms vary vastly from one person to another so tracking your symptoms may be a great way for you to better understand how your cycles affect you. You can keep track of your symptoms (moods and pain) in the Natural Cycles app, from the Add Data page. If you don’t see these in your app, click here to see how to enable trackers in your app.
Visit this link to learn more about 5 ways to manage PMS.