When a man becomes sexually excited, he may have an orgasm (ejaculates) and release fluid (semen or cum) that have millions of sperm cells. When the penis is inside the vagina (intercourse), sperm may be released inside of the vagina. It is possible for sperm released close to the outside of the vagina to swim into the vagina. Once inside the vagina, sperm swim upwards through the opening of the cervix, through the uterus, and into the fallopian tubes. Sperm can live up to six days inside a woman. Even though the journey is a short six or so inches, it’s a difficult path, and only a few sperm will reach the woman’s fallopian tube. A woman releases an egg (ova) every 30 days or so from one of her ovaries into one of her fallopian tubes. There is one ovary on either side of the uterus. Usually one ovary will release an egg one month, and then the other ovary will release an egg the next month. If an egg is in one of the tubes, a sperm can join it (fertilize it). Once fertilized, the egg forms a single-celled unit called a zygote, and the change prevents any other sperm from getting through to the egg. In the case of twins or multiples, it is possible for a woman to release more than one egg and for each to be joined by a sperm. This is how fraternal twins (multiples) are made. Identical twins are developed from a single fertilized egg that splits. Identical twins have nearly the same genetic makeup, but fraternal multiples are like any other sibling. The zygote(s) divide(s) rapidly for a few days in the tube and then travels down into the uterus. It can take another couple of days for the zygote(s) to connect (implant) inside of the uterus for a pregnancy to begin. Um, can I get pregnant if…? Myth and facts from our friends at Bedsider Bedsider: Pregnancy 101 Planned Parenthood: How do you get pregnant?