There is no absolutely safe time to have sex and not get pregnant. If you have sex without using contraception, pregnancy can happen at any time during the menstrual cycle, even during, or just after, the period.
A woman can also become pregnant even if she has never had a period before, during her first period, or after the first time she has sex.
There is no 'safe' time of the month when you can have sex without contraception, and not risk pregnancy. However, there are times during a menstrual cycle when a woman is at her most fertile and this is when she is most likely to conceive.
The menstrual cycle begins on the first day of her period and continues up to the first day of her next period. She is most fertile at the time of ovulation, (when an egg is released from her ovaries) which usually occurs 12-14 days before her next period starts. This is the time of the month when she is most likely to get pregnant.
It is unlikely she will become pregnant just after her period, although it can happen. It is important to remember that sperm can sometimes survive in the body for up to seven days after having sex. This means that it may be possible to become pregnant soon after her period finishes if she ovulates early, especially if she has naturally short menstrual cycles.
It is not likely that pregnancy can occur from anal sex. It is possible, however, if sperm inadvertently flows out of the anus and onto the vagina. The possibility is remote, but it could happen.
You should always use contraception when you have sex if you do not want to become pregnant.