Can a girl get pregnant if she's on top with no condom?

I was wondering why we were getting this question a lot lately. Then last week, I saw the movie ‘Knocked Up.’ Lo and behold, one of the characters in the movie claims (and exclaims) that a girl can’t get pregnant if she’s on top⁠ (top: In sexuality, this is someone who wants to take the/a lead during sex with a partner or partners, or to consensually take the role of being in charge of sexual actions.) . ‘Cause of gravity and all that.

WRONG! So totally not true!!!

Yes, women can get pregnant if they are on top and the man ejaculates into her. Granted, yes, gravity works against the bulk of the semen⁠ (semen: Fluid which comes from the urethra of the penis during ejaculation, and which usually contains sperm.) , and a lot of it can dribble back out⁠ (out: Short for ‘out of the closet’. When someone’s LGBTQ+ identity is known to other people.) . But there is usually enough residue in there to allow some sperm⁠ (sperm: Reproductive cells of people with penises which can fertilize an ovum and create pregnancy.) to make their way into the reproductive tract. On a very microscopic level, there are special mucus proteins in the cervix⁠ (cervix: The opening to the uterus, the bottom of which is at the back end of the vagina.) that help guide the sperm up into the body as well as tiny “fingers” called cilia on some of the epithelial cells in the reproductive tract that work to sweep sperm towards the upper reproductive tract. Remember folks, nature wants you to reproduce. That doesn’t mean it’ll happen at the most opportune times. But nature has been around far longer than you or me, and a simple ploy like waiting for gravity to cause sperm to leak out of the woman isn’t going to outsmart or suffice against millions of years of evolution.

Instead, if you really want to prevent pregnancy⁠ (pregnancy: The state of carrying a developing embryo or fetus within the uterus. Medically, someone is considered to be pregnant when an egg has been fertilized by sperm, cells divide, and the fertilized egg is implanted within the lining of the uterus.) , the man needs to wear a condom⁠ (condom: A thin sheath or tube of latex or another material, worn over the penis during sex to prevent or reduce the risk of pregnancy and/or sexually transmitted infections.) , and the woman can use a second method of birth control⁠ (birth control: Any number of methods people use to intentionally prevent unwanted pregnancy, including the condom, the cervical barrier, the implant, the patch, the pill, the rhythm method, the ring, the shot, the IUD, spermicide and withdrawal.) like hormonal birth control pills, a diaphragm or cervical cap.

For more info, please read:

• What’s the Risk? Easy Pregnancy Risk Assessments
• Safe, Sound & Sexy: A Safer Sex How-To
• Condom Basics: A User’s Manual

By the way, if anyone cares, I really liked ‘Knocked Upexternal link, opens in a new tab.’ I thought it was freakin’ hilarious, and the story was actually pretty sweet. Rent it if you haven’t already seen it.