The Calendar Method & Other Natural Birth Control Myths

Natural Birth Control

Here is a list of the most common myths about the calendar method and natural birth control.

It’s my intention this article will help you separate fact from fiction; why the calendar method is ineffective at preventing pregnancy, but how another natural method is as effective as the pill(!) and if natural birth control could be a right fit for you.

Let’s go…

Calendar Method & Contraception

The family planning calendar method is NOT an effective contraception because it is based on past cycles to mathematically predict when ovulation will occur.

Women are incredibly unique and our cycles — including ovulation — can commonly fluctuate from cycle to cycle. This can occur due to stress, becoming ill such as catching a cold, even exposure to light at night to name a few.

A math formula does not take this into consideration and should not be used as birth control.

Calendar Method & Safe Days

The calendar method uses past cycle lengths to predict the day of ovulation — assuming it will be at the same time each and every month — which is a myth. And so these ‘safe days’ relating to the calendar method would not be accurate.

The only way to effectively tell if you are safe is to observe fertility signs (like in the effective sympto thermal method) to have confidence in which days will not lead to pregnancy.

Calendar Method & Science

Since the 2000’s, multiple scientific studies have indicated the existence of a fertile window and that it can be observed relatively easily once learned and by recording one’s own fertility signals.

A woman’s fertile window can be detected with a high degree of accuracy from basal body temperature measurements and cervical fluid. A math equation absolutely goes against what the scientific studies have learned about a women’s menstrual cycle and her fertility.

Calendar Method of Family Planning & Other Innective Methods

Other common names of this calculation method like the calendar method of family planning, the standard days method and the rhythm method. All three are outdated and unreliable as they do not involve observing fertility signs.

Calendar Method & Fertility Awareness

The calendar method can often incorrectly be mixed up with the practice and term ‘fertility awareness’. But it’s quite the opposite: fertility awareness methods observe one’s fertility signals whereas the calendar method does not.

Please note that practicing the calendar method is not an effective contraception and will likely lead to pregnancy at some point. Where as the sympto thermal method of fertility awareness has been found to be highly effective (99.4%) by a study in 2007. This rate is on par with perfect use of the contraceptive pill!

I hope this post was educational in sharing that the calendar method is an outdated and inaccurate form of contraception.

If you have been using the calendar method, or you’ve been thinking about trying it, you may like to learn this effective method instead. If you’re not in a position to handle an unintended pregnancy, the calendar method is not recommended. Be safe and do your research on effective contraceptive or fertility awareness that is the right fit for you.


What’s the calendar method of FAMs?

Calendar-based contraceptive methods.

Timing of sexual intercourse in relation to ovulation. Wilcox et al. New England Journal of Medicine 1995; 333:1571-1521. 

FAM is 99.4% effective when used correctly. P.Frank-Herrman et al. Human Reproduction 2007; 22:1310-1319.

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Wonderful Within is a blog designed to educate and empower women from within. We talk all things wonderful, including: menstrual cycles, periods, charting, fertility awareness and women’s health and wellness choices.


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