Pop quiz: When having sex, how deep does semen need to get for pregnancy to occur?
Answer: Not that deep.
Even semen around the vaginal area or the vulva, even if it’s not inside the vagina, can lead to pregnancy.
Semen is the thick white fluid that comes out of a penis during ejaculation. This fluid contains millions of sperm cells, and if one of these millions reaches the egg cell then pregnancy occurs.
So, sperm cells themselves cause pregnancy, not the semen. The semen is there to provide food for the sperm and helps it survive, but the sperm is able to swim to the egg even without much help from its fluid transport.
Also, when aroused, the vagina provides assistance to the sperm by producing fluids that lubricate the pathway into the vaginal opening. This creates an environment the sperm can swim and survive in until it reaches the egg (which is found in the fallopian tube when a woman is fertile).
Of course, pregnancy is still more likely to occur when sperm gets directly into the vagina, since this makes the sperm’s trip to the fallopian tube much easier. But it’s still possible that pregnancy can happen even if the semen only gets on the vaginal area.
So the next time you try "planning your family" by avoiding penetration, think again. Semen doesn't need to be ejaculated inside the vagina for pregnancy to occur.