Q: Is it possible to get pregnant from masturbating, after touching a doorknob that might have dry semen on it?
A: It is very common for people to feel anxious about becoming pregnant, especially if they are not ready or interested in becoming pregnant. Thankfully, in this scenario, it is extremely unlikely for a person to become pregnant from coming in contact with dried semen and then masturbating. I know of no documented cases of this happening.
Semen transports sperm — as well as nutrients such as fructose, proteins and enzymes that support the survival of the sperm. When sperm comes in contact with oxygen, damage occurs to the important structures within the sperm. As semen dries, the sperm become damaged and are unable to fertilize an egg, even in the very unlikely scenario that you described.
Of course, touching unclean surfaces or objects and then putting your hands in your vagina could introduce bacteria or other irritants into the vagina. If you are worried about this, you might wash your hands before masturbating.
Additionally, if you are not ready to become pregnant and you want to prevent to a pregnancy in the future, you may ask your healthcare provider, or learn more about contraceptive methods that are right for you — including condoms, the birth control pill, the ring, the patch, IUD or the implant. Learn more about these and other birth control methods on our Kinsey Confidential website.