sexual intercourse
The Women's vagina. :^)
sperm
Sexual Intercourse, when the penis enters the vagina and ejaculates.
If he deposited sperm in your vagina and you ovulated, you could be pregnant. No sperm, no baby.
Sperm needs to be deposited inside the vagina during sexual intercourse for pregnancy to occur.
vas deferens
If it is deposited in the vagina (internally, not externally) and it contains sperm you could become pregnant.
During the act known as "sexual intercourse", the male penis goes inside the female vagina, where (usually after moving back and forth for a while, to get excited), the semen (the liquid which includes the sperm cells) is deposited inside the woman's body.
It is called Fertilization.
Removal of Mirena does not affect whether sperm is in the vagina.
What is leaking from the vagina is not the 'cum' all together. the semen, or the liquid that protects the sperm from the women's natural defences, have no reason to remain in the vagina once the sperm have collected into a place called 'the sperm pool' which holds the sperm until the cervix or the small opening that leads to the uterus opens and allowd the sperm to move in and find the egg. Thus the semen is leaked back out of the vagina, since it is not needed in the body anymore.
The process when an egg cell and a sperm cell COMBINE is called Fertilization