A man who performs withdrawal will pull his penis out of the vagina before he ejaculates. Of every 100 women whose partners use withdrawal, four will become pregnant during the first year of perfect use. Pre-ejaculate can contain enough sperm to cause pregnancy.
Pregnancy is also possible if semen or pre-ejaculate is spilled on the vulva.
Withdrawal offers no protection against sexually transmitted infections. The men who use withdrawal must be able to know when they are reaching ejaculatory inevitability - the point in sexual excitement when ejaculation can no longer be stopped or postponed. The man withdraws his penis from the vagina before or when he feels he has reached the point when ejaculation can no longer be stopped or postponed. He ejaculates outside the vagina, being careful that semen does not spill onto his partner's vulva. Some men cannot tell when they are going to ejaculate.