Natural fertility methods: Part I

Fertility calendar

The oldest and most known natural conception methods id the Ogino-Knauss, also know and Rhythm Method or Fertility Calendar that enables through math calculus determine the fertility days of the couple, considering the women ovulates once a month 14 days before the next menstruation and the ovule only lives 48 hours after ovulation and the spermatozoid 72 after ejaculation.

When the periods are regular the calendar method is useful, but if you have an irregular period then this method will present many mistakes because the time between the previous menstruation and ovulation depends on the hypophisis, and this relies on the hypothalamus and this on the encephalon, thus that any symptom of stress is able to make ovulation get delayed or bring it forward. Unlike this is the second phase that is always regular in each woman en approximately two weeks between the ovulation and the nest menstruation.
The calculus are done considering 12 previous periods, you rest 19 days to the shortest (S) period and 11 to the largest (L) period, so the fertility formula would be like this:

* S-19 * L-11

Let’s make an example, if the 12 previous periods were of 28, 27, 31, 32, 28, 30, 29, 32, 30, 28, 32 and 28 days; the shorts would be the 27 and the largest of 32. Thus, we have:

* 27-19=8 *32-11=21

Giving as a result that the couple would be fertile from the 8th to the 21st day, and if they decide to put off the pregnancy they can have sex from the 1st day of menstruation until the 8th day, and from the 8th and further on they must keep sexual abstinence until the 21st day, from which they can catch up on your sexual life.

Beware: This method has only a 64% of security.