In planning of family knowledge of regularities of fertilization of an ovum is absolutely necessary. The calendar of conception allows to have always an idea of in what days the probability to become pregnant is highest and in what — is practically absent.
Knowledge of the calendar of own menstrual cycle will allow with a considerable share of probability to plan conception of the child and also to count days when fertilization least all is possible. It is the best of all to be able to calculate the period of the increased fertility without online calculators.
To calculate the calendar of conception, it is necessary to know duration of all cycle and duration of periods. The woman should fix for at least half a year start dates and the terminations of monthly. On the basis of these data it will be possible to get an idea of the average duration of a cycle. The ovulation moment usually falls on its middle. At this time the ripened ovum leaves a follicle in a funnel of a fallopian pipe.
Fertilization is possible within 24 hours after a rupture of a follicle, in rare instances — during 36. Then the ovum perishes.
As a result of hormonal failures and other factors the ovulation can sometimes come before term. Therefore the period between the termination of periods and the middle of a cycle is considered favorable for conception. Fertilization probability is about 33% at this time. But in 36 hours after an ovum exit the pregnancy becomes almost impossible to the following ovulation.
The term of life of spermatozoa is 2–3 days, is rare — 5–7. Therefore conception is possible even if the unprotected sexual intercourse happened some days before an ovulation. Spermatozoa will wait for the ripened ovum in uterine tubes.
Calculation of the ovulyatorny period considerably is at a loss in case of an irregular menstrual cycle. The phase of maturing of an ovum — estrogenovy — can have every time different duration. However the second phase of a cycle, progesteronovy, cannot exceed 16 days. Therefore to calculate approximate time of an ovulation, it is necessary to take away from duration of each cycle 16 days. This method will help to calculate for what days an ovum exit on average is necessary. Observations of own organism will help to increase the accuracy of definition of day of an ovulation. Observation of basal body temperature is considered the most exact auxiliary method. It is necessary to take measurements every morning on an extent not less than half a year, strictly at the same time. In day of an ovulation temperature decreases approximately by 0.5 degrees, and then again accepts usual value. It is possible to learn about approach of the period, favorable for conception, and on a condition of the emitted cervical slime. Its quantity increases, and the viscosity decreases. Increases in sexual desire and nagging pains also peculiar to some women in the bottom of a stomach can be indirect signs of approach of the ovulyatorny period. Use of a method of calculation of day of an ovulation not too is good as an effective way of contraception. Reliability of use of the calendar of conception for the purpose of prevention of unwanted pregnancy does not exceed 60%. And here it is possible to increase fertilization probability with its help, on the contrary, rather easily.