Contraception > Methods said to be "natural"

Interrupted coatis (pulling out)

This method rests exclusively on the man: it means that he pulls out (removes his penis from the vagina of his partner) before ejaculation.

Reliability: absolutely none. There is no guarantee of self-control. Also, spermatozoids are present in the secretions not counting that drops of sperm can leak before final ejaculation.

Advantages: the least expensive of all methods, along with total abstinence.

Inconveniences: frustration.

The Ogino-Knaus (rhythm) method

This method is based on statistics and on the observation of bodily changes.
Statistics: it means observing the length of cycles by carefully noting the dates of your period, first to verify the perfect regularity of your cycle (not very common!) and then, to determine the period of fertility which is said to be approximately 14 days before the beginning of your next period. You then abstain from all sexual relations at this time, more or less from the 10the to the 17th day after your period.
Bodily changes: The hormone progesterone secreted after ovulation increases the body temperature by a few tenths. Taking your body temperature regularly in the morning upon waking up allows you to notice this temperature increase and to verify that ovulation has taken place.

Reliability: absolutely none. This method, very fashionable in the 50's et 60's, largely contributed to today's rampant demography!

Advantages: you only need a pen, a calendar and a thermometer.

Inconveniences: not only is this method inefficient (or very risky, if you prefer) it is also extremely stressful, inconvenient and complicated...