# How to calculate dangerous days for pregnancy

You will need
• - the calendar;
• - thermometer;
• - notebook.
Instruction
Please note that this method consists in observing a woman for her menstrual cycle for half a year. This helps to more accurately determine its fertile phase, or the phase of ovulation, the time favorable for conception.
It should be borne in mind that in a healthy woman ovulation (the release of an egg from the ovary) occurs approximately in the middle of the menstrual cycle - the interval between menstruation. Since fertilization takes place with the participation of male and female germ cells, the definition of “life-threatening” days for pregnancy makes sure that their “life expectancy” is taken into account. As a rule, in an egg cell it is up to 2 days, and in a spermatozoon - 2-4 days.
To determine the fertile days, select the menstrual cycles with the shortest and longest duration. For example, it is 27 and 30 days.It is necessary to subtract 18 (27-18 = 9) from the value of 27, while 18 includes 14 days (the average period from ovulation to the next menstruation) and 4 days of viability of spermatozoa. From the number 30 we subtract 11 (30-11 = 19), 11 is 14 days from ovulation to menstruation and another 3 days for insurance. We get a “dangerous” period for pregnancy from the 9th to the 19th day of the menstrual cycle. However, the exclusion of 10 days of normal sex life is not suitable for every woman.
To calculate the "dangerous" days for pregnancy, you can use the method of measuring basal temperature, which is more convenient and reliable. The procedure is performed every morning after waking up, but before getting out of bed, for three months. According to the obtained indicators, basal temperature graphs are compiled. At the beginning of the menstrual cycle, it fluctuates within 36.6-36.7 ° C, at the time of ovulation it becomes even lower (36.2-36.4 ° C), after which it rises sharply and stays for about two weeks at around 37, 0 ° C To determine the period favorable for conception, you need to add to the ordinal number of the day of the cycle on which ovulation was noted plus or minus three days (the average lifetime of the sperm cell).