To determine which days of cycle to have unprotected sex is dangerous, you must know the day of ovulation. During this period, the ripened egg leaves the ovary and enters the womb. The lifespan of an egg is approximately day. If at this time she will meet with the sperm, conception will take place. In order to identify the time of ovulation, you should pay attention to basal temperature (measured in the rectum), vaginal fluids and cervical position.
Measure basal temperature every morning, not rising with bed. Insert the thermometer into the rectum at 5 cm Readings take approximately 10 minutes. On ordinary days the temperature did not exceed 37 degrees. The day before its increase is the date of ovulation.
Pay attention to your vaginal discharge. After menstruation has dry in a few days goo appears white or yellowish. But closer to ovulation, it liquefies and becomes watery transparent mass. After ovulation takes place, the discharge becomes thick and less abundant.
After menstruation daily palpate the cervix to determine its position. In normal condition it is solid, flat and closed. But during ovulation the cervix is undergoing significant changes - it becomes a soft, somewhat lax, and rises and opens.
Take the number comprising the total duration of the menstrual cycle and subtract 11, then subtract 8. The resulting number will be the date of the first threat of the day. Then add to the number 8 and get the date of the last threat of the day. The Central date of this period is the date of ovulation. Example: cycle length of 28 days. Count: 28-11-8=9 (ninth day of the cycle - the first of the dangerous days). Then add: 9+8=17 (the seventeenth day of the cycle - the last of the threat). Now, find the date of ovulation: 17-4=9+4=13 (the thirteenth day of cycle is most favorable for conception). Count the length of the cycle to the first day of menstruation.
Watch for a duration of at least six menstrual cycles (since cycles most women have irregular). Subtract 11 from the number of days in your longest cycles (for hedging can be deducted from 8 to 11 days). This way you define the last of the dangerous days in your menstrual cycle. The number of days in the shortest of your last menstrual cycle, subtract 18 (may insure and deduct 19-21 days). This will help you to identify the first dangerous days of the cycle.
In fairness it should be noted that all these calculations are rather conditional, since the menstrual cycle is unstable for most women. So do not completely rely on such a method of protection from unwanted pregnancy.