The symptoms-based method is a fertility awareness method that uses your body’s signals to determine when you’re fertile and when you’re not.
This article is part of our Contraception Series!
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Note: the information below was sourced from references (1-5), unless stated otherwise.
What is it?
The symptoms-based method is a fertility awareness method that uses your body’s signals to determine when you’re fertile and when you’re not. The idea is that you can have sex without using other contraception on the days that you’re supposed to be non-fertile. Of course, you can still have sex on fertile days, as long as you use a different contraception on those days (for example, a condom).
How does it work?
Your body gives different signals throughout your cycle that indicate what phase of your cycle you’re in. One of them is temperature. This is a common method of measuring when you’re fertile. This method relies on the fact that your body temperature will increase slightly (about 0.1 to 0.2 degrees Celsius) after your fertile days. For this method to work, you have to measure your temperature every single day when you wake up – before you do anything at all - and record what you measure. Only then can you find a pattern in your temperature that allows you to determine when you’re fertile.
A different variety of the symptoms-based method is called the two-day method. Here, you touch the entrance of your vagina every morning and record whether there’s moisture present there. If there is no moisture whatsoever for two consecutive days, you’re able to have sex. This method is based on the fact that vaginal secretions change in amount and texture throughout the cycle, becoming more copious and thinner around ovulation.
To make the symptoms-based fertility awareness method more effective, you should combine multiple symptoms (for example, both temperature and moistness of the vagina in the morning).
The time between menstruation and ovulation is a tricky time to have unprotected sex, because ovulation is often not as predictable as we want it to be. After ovulation, however, you’re quite reliably non-fertile - though it's also hard to pinpoint exactly when you're ovulating.
In order to use a fertility awareness method reliably, you need to receive high-quality counselling. Ask your doctor whether they can provide this to you, or perhaps to refer you to an expert.
How effective is it?
There is not a lot of data showing how effective fertility awareness methods are. It is estimated that with perfect use, the two-day method is about 96% effective, meaning out of 1000 people* using this method, around 40 will become pregnant per year. The temperature-based method is thought to be around 99.6% effective with perfect use, meaning about 4 people* out of 1000 will become pregnant within a year.
Estimates for typical use range from 20 pregnancies per 1000 people* per year (98% effective) to 230 pregnancies per 1000 people* per year (77% effective). Higher rates of pregnancy are more likely when you haven’t had good counseling on these methods by a medical professional.
What are possible side-effects?
There are no side-effects of a fertility awareness method.
When can't I use it?
When you’re unable to remember to track your temperature or other symptoms every morning around the same time. If this is difficult for you, a hormonal method or barrier method might be more suitable.
Irregular cycles with irregular symptoms are more common in the two years after your first period, around menopause, after childbirth, and after abortion. Use of this method is therefore not recommended in these periods.
You also shouldn’t use this method if you have genital bleeding for an unknown reason, if you use any drugs that could affect the regularity of your cycle, your hormones, or fertility signs (for example, lithium, certain medications for depression and anxiety, several anti-inflammatory drugs, and more), or if you have a disease that increases your body temperature (for the temperature method), including fever.
Lastly, you shouldn’t use a fertility awareness method when you have a condition that puts you in great danger if you do become pregnant. These methods are not reliable enough to protect you in this case.
Does it work immediately?
Generally, no. You have to track your cycles for at least six months to gain enough insight into your body’s patterns to correctly estimate when you might be fertile (6). You should also keep an eye on changes in these patterns to notice in time when your cycle lengths start changing.
What happens to my fertility if I stop using it?
Since nothing in your body changes when using this method, nothing’s different when you stop using this method. You have a higher risk of pregnancy if you’re not tracking your fertile days, because you won’t know when your fertile days will be.
Does it protect against sexually transmitted diseases (STDs)?
No, fertility awareness methods do not protect against STDs. If you’re having sex with someone new or untested, use a barrier method as well.
*People, here, means anyone who is able to become pregnant, including girls, women, and non-binary people and transgender men who still have their uterus, vagina, and ovaries.
Are you curious about other methods to protect yourself from an unwanted pregnancy? Read about other birth control options here!
This article is pending medical review.
Written by Juliëtte Gossens
Reviewed by Sophie Oppelt and Selina Voßen
Edited by Juliëtte Gossens
McFarlane I (ed.). Seeing the unseen: The case for action in the neglected crisis of unintended pregnancy. United Nations Population Fund. 2022. Available from: https://www.unfpa.org/sites/default/files/pub-pdf/EN_SWP22%20report_0.pdf
Hacker NF, Gambone JC, Hobel CJ (eds.). Hacker & Moore’s Essentials of Obstetrics & Gynecology. 6th ed. Philadelphia: Elsevier; 2016.
Hoffman BL, Schorge JO, Halvorson LM, Hamid CA, Corton MM, Schaffer JI (eds.). William’s Gynecology. 4th ed. New York: McGraw-Hill Education; 2020.
Centers for Disease Control and Prevention. The United States Medical Eligibility Criteria for Contraceptive Use, 2016 (US MEC). Available from: https://www.cdc.gov/reproductivehealth/contraception/mmwr/mec/summary.html
Centers for Disease Control and Prevention. 2016 U.S. Selected Practice Recommendations for Contraceptive Use (U.S. SPR). Available from: https://www.cdc.gov/reproductivehealth/contraception/mmwr/spr/summary.html
Fertility UK. Avoiding Pregnancy. Available from: https://www.fertilityuk.org/new-page-1 [Accessed September 21st, 2022]
Please note: the information we provide to you here is for educational purposes only. If you’re experiencing any discomfort or have any complaints or questions about your health, please contact your doctor or other relevant health professional. We don’t provide medical advice.