Emergency contraceptive methods

In certain circumstances when using Natural Cycles, you might consider taking emergency contraception in order to prevent a pregnancy. These circumstances include having unprotected sex on a red day, the failure of your contraceptive method used on red days (e.g. condom breaking) or in very few cases, the Natural Cycles algorithm giving you one or more incorrect green days. This is known as the method failure rate which is 0.5% per year. If the algorithm give you an incorrect green day with risk of pregnancy, you will receive a message in the app.

If you decide to use an emergency contraceptive, you have two options to choose from; the emergency pill and the copper IUD:

Emergency Contraceptive Pill
If you choose to take an emergency contraceptive pill (also known as the morning after pill, Plan B, or EC pill) there are some very important things to keep in mind.

There are two different kinds of emergency contraceptive pills containing either levonorgestrel or ulipristal acetate. Pills containing levonorgestrel must be taken within 72 hours (3 days) of unprotected intercourse or contraceptive failure. Pills containing ulipristal acetate must be taken within 120 hours (5 days) of unprotected intercourse or contraceptive failure.

Will it prevent a pregnancy effectively?

It is important to remember that the emergency contraceptive pill does not work if you have already ovulated. If taken before ovulation, it is highly efficient.

You can see directly in your Natural Cycles app if you have ovulated yet or not.

A paper published in 2010 combined the results of two clinical trials and showed that:

     of 1,714 women who received ulipristal acetate, 22 (1.3%) became pregnant

     of 1,731 women who received levonorgestrel, 38 (2.2%) became pregnant

Remember to always carefully read the patient information leaflet on use of the pill

What to think about after taking an emergency contraceptive pill.

  1. Add #EmergencyPill in your Notes inside the app.​

  2. Log your period.​
  3. ​​​Take a pregnancy test 3-4 weeks after the emergency pill, regardless of whether your period has started or not, to rule out a pregnancy.​
​​​​⚠️ Don’t measure your temperature until your natural period has started. The emergency contraceptive pill increases progesterone hormone levels in your body which has an impact on your temperature and delays ovulation. Continuing to measure your temperature may lead to an inaccurate detection of ovulation and an incorrect fertility status.

⚠️  Use protection for the remainder of your cycle until you get your period.

⚠️  Once you have taken the pill, you may experience some bleeding - this is not equivalent to your period.

You can mark the bleeding that occurs after having taken the emergency contraceptive as spotting in the app if you would like to keep track of it. Once you have your period (after roughly 2 weeks) be sure to mark this as a period 

Since ovulation has been postponed, your cycle will automatically become longer.

Please read Natural Cycles' Instructions for use for more information on how to manage your app following use of emergency contraception.

Copper IUD

The copper IUD has to be inserted within 120h (5 days) from unprotected intercourse or failure of contraceptive method.

A study has shown that the insertion of a copper IUD by a healthcare professional is an effective means of emergency contraception.
A negative test should be taken 3-4 weeks after insertion of a copper IUD, to rule out a pregnancy. The IUD can be removed after a negative pregnancy test if preferred.

The copper IUD will also have no impact on your cycle as it does not release hormones.


Please do remember that we always strongly recommend using condoms during your red days. Read more here about what protection to use on red days.

If you are unsure whether or not an emergency contraceptive method is needed, please consult your doctor.

* This information on emergency contraception is provided for educational purposes only and is not intended to replace the advice of your healthcare professional. Please consult your doctor or health professional before starting emergency contraceptive treatment.”