It is possible to get pregnant if you have unprotected sex on the third day of your period.
The menstrual cycle is the interval from the first day of the current period to the first day of the next period, and 21 to 35 days are within the normal range.
If the menstrual cycle is 28 days, ovulation will occur on the 14th day of the cycle; and if you have unprotected sex on the third day after menstruation, the sperm will survive in the woman’s body for about 3 to 5 days, so there is a possibility of pregnancy in the 5 days before a woman ovulates (including the third day after menstruation), only the probability of pregnancy is small.
However, for women with irregular menstrual cycles, it is impossible to accurately calculate the ovulation period, and sex at this time also has the possibility of pregnancy.
If you do not need to have children, you need to take contraceptive measures to avoid the harm caused by unwanted pregnancy.