Frequently Asked Questions

No. The Rhythm method is unreliable and is not utilised as a modern fertility awareness method (FAM) of family planning. 

Current evidence-based Natural Family Planning in Australasia involves: the Billings Ovulation Method^®, the Creighton Model System, and the Sympto-thermal method.

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Unfortunately, this is incorrect and misleading. This low estimated figure was obtained from retrospective surveys in 1995 and 2002 that pooled data for all FAMs including the rhythm method, without differentiating the higher effectiveness of other individual FAMs.
It has repeatedly been misrepresented erroneously by academic publications² and by organisations that do not have expertise in fertility-awareness.
More correct contraceptive effectiveness rates for FAMs are significantly higher³ and are comparable with other hormonal methods of contraception:

It must be noted that Typical use effectiveness relates to how the couple uses the FAM, and is usually lower than Method efficacy due to couples choosing to have intercourse during known fertile times. Clearly not the best choice if the aim is for contraception!

Method efficacy rates can and should be able to be achieved with appropriate instruction from qualified and currently certified FAM Teachers/Educators and adherence to the FAM instructions.

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The probability of achieving a pregnancy is highest when intercourse occurs on the peak/ovulation day. Published probabilities range from 0.10 when intercourse occurs six days before ovulation to 0.33 when it occurs on the day of ovulation itself¹⁰.

Timing intercourse with ovulation is also advantageous in determining whether investigation for subfertility may be required earlier, or otherwise delayed to give the couple the opportunity to try for optimum timing.  
Knowing when the fertile time is occurring also allows couple to be able to plan to be together, particularly around ovulation.

Also, be aware that regular intercourse every 2-3 days has disadvantages such as interference with travel or work commitments, additional stress of 'being available'.  This is especially so if the woman’s cycle is long or irregular and without necessarily knowing if each act of intercourse is during an infertile or fertile time.

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Performing a “day 21” progesterone level (in infertility workup) is supposed to be a measure of mid-luteal phase progesterone. In practice, though, “day 21” does not necessarily correspond to a mid-luteal measurement since this timing itself relies on the Rhythm method and a regular 28-day menstrual cycle.
A “day 21” progesterone level alone also does not give adequate information about the various luteal phase deficiency subtypes.
One recent study found only 15% of woman had a 28-day menstrual cycle.⁷ 
A true mid-luteal point for measuring progesterone can be determined by women or doctors/teachers familiar with FAMs.

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The majority of smartphone apps rely on either either calendar-based or symptom-based methods.
Recent studies have demonstrated the lack of reliability of these apps for predicting ovulation^7,8. On the other hand, fertility awareness methods based on cervical mucus have high reliability in identifying ovulation and fertile/infertile times in in the menstrual cycle⁹.

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Absolutely. FAMs are appropriate for and can be used successfully by women who have irregular cycles.

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