Can I ovulate during my period?
No, you can’t ovulate during your period.
Can I get pregnant while on my period?
While this is rare, it is technically possible to get pregnant if you have sex while on your period. This is due to sperm survival, as sperm can survive in the female reproductive system for up to five days.
This means that in some cases where the cycle length is very short, the sperm and egg could still meet after you’ve had sex on your period, increasing the chances for pregnancy. This could happen if you ovulate very early in the cycle and/or experience longer periods. For instance, if you ovulated on Cycle Day 11 (CD 11) in this cycle and your period lasted for 7 days, this means that you were fertile on CD 6 and CD 7, while you were still on your period.
You can read our Cycle Matters post on whether you can get pregnant on your period here.
How long does an average period last?
Our data tells us that most Cyclers bleed for an average of four days. However, this varies from person to person and can change from cycle to cycle too. Learn more here.
When does ovulation occur during the cycle?
According to our data, the average ovulation day is Cycle Day 18. Again, this can vary from person to person and cycle to cycle. On your Cycle Insights page (accessible from the Today view > See cycle insights), you can see your own average ovulation day.
Will the algorithm take early ovulation into account?
Early ovulation is taken into account in calculating red and green days, particularly when the algorithm is still learning about your cycle when you first join Natural Cycles.
The algorithm adds a buffer of red days as a safety margin while calculating red and green days around the fertile window. This buffer is more extensive during the first three cycles of use. After that, it becomes smaller if your cycles are regular, potentially giving you more green days in later cycles. While the algorithm learns your cycle, this larger buffer helps protect against potential early ovulation. However, you will always get a buffer of red days before ovulation based on your individual cycle pattern. Should your cycle be irregular (if your ovulation day moves considerably from cycle to cycle), the buffer will remain large, and you may experience a higher number of red days than users with less variation in their cycles.