By not having intercourse pregnancy will not occur.
By calculating the days on which ovulation may occur, the fertile period during the menstrual cycle can be estimated. The chance of pregnancy can be reduced by not having intercourse on the days within the fertile period. This method is relatively unreliable since the length of menstrual cycle may differ from month to month.
Another way of assessing the fertile period is measuring body temperature of the woman (daily). Based on temperature fluctuations, the fertile period can be estimated and intercourse on these days should be avoided in order to prevent pregnancy. As with periodical abstinence, this method is relatively unreliable due to inter-cyclic variations.
In order to prevent the sperm from reaching the ovum, the penis can be withdrawn from the vagina before ejaculation. Although this method reduces the chance of pregnancy, it is a relatively unreliable method since sperms can already have entered the vagina before ejaculation.
By washing the vagina using water after intercourse in order to remove the semen from the yoni, the chance of pregnancy may be reduced. This method is unreliable.