Calendar method of contraception (method of safe days), it still name a rhythmic method — one of methods of natural contraception. The method consists in calculation presumable date of ovulation and abstention from sexual contacts in fertile a phase. The fertilnaja phase is a phase ovulation, that is that time when the woman can become pregnant.
The calendar method of protection from undesirable pregnancy is simple enough in use. It is necessary to know the cycle. This method women, at which menstrual can easily use a cycle constant. Supervision over a cycle are necessary for conducting within several months (a calendar ovulation), and it is even better – that there was data for last 2 years. That, it is necessary for women at whom the cycle not constant, is better to refuse use of a calendar method of contraception, but a message menstrual a calendar all the same. At once we will make a reservation what precisely to define safe days difficult, even it is almost impossible, because viability sperm in a vagina is very high also all this time they are capable to cause fertilisation if will come ovulation.
Ovulation occurs approximately for 14-15 days prior to the beginning menstruation, it is viable ovary after ovulation about 24 hours, sperm keep activity in an organism of the woman till 5-7 days. fertile phases define the beginning by subtraction 18 of the shortest cycle, and the end – subtraction 11 of the longest.
EXAMPLE OF USING CALENDAR METHOD
Short cycle — 28 days, long – 30 days.
The beginning fertile phases – 28-18=10-th day of a cycle,
The end – 30-11=19-th day of a cycle.
I.e. with 10 for 19 day there can be a fertilisation and these days it is necessary to use barrier methods of contraception or to abstain from sexual contacts.
It is possible to carry its unreliability as he assumes ideally regular menstrual a cycle which any woman does not possess to lacks of a calendar method. Too often there are every possible failures. Even the most healthy women have situations when ovulation does not come in general, and menstruation come in time.
It is possible to name a calendar method of contraception more likely a method of planning of pregnancy, rather than a contraception method, too it strongly depends on unforeseen circumstances, and it is impossible to calculate precisely approach term ovulation.