It's one of those facts that sounds like it was made up just to make kids terrified of having sex: It's possible to get pregnant from penis-in-vagina sex — even if nobody orgasms. Surely not, right? But as it it turns out, the rumors are true. It’s rare, but still possible to get pregnant from precum, the liquid that comes out of the penis during arousal, but before ejaculation.
As Planned Parenthood explains, “Precum (also known as pre-ejaculate) is a small amount of fluid that comes out of the penis when you’re aroused, but before ejaculation happens. It doesn’t usually have any sperm in it. But some people’s precum does have a small amount of sperm in it, sometimes. This means sperm can get into the vagina and possibly fertilize an egg.”
Let’s talk numbers: One 2011 study found that, in a sample of 27 cis men, 41% had pre-cum that contained spermatozoa, and for the majority of those cases (37% of all the men in the study), “a reasonable proportion of the sperm was motile.”
There’s no way to tell whether an individual’s precum contains sperm at any one time, so, as Planned Parenthood puts it, “that’s one reason why the withdrawal method (pulling out) isn’t the best at preventing pregnancy.” In typical use, about 22 out of 100 people who use the pull-out method as their sole form of birth control get pregnant every year — that’s over 20%. (Besides the precum factor, it's also difficult to pull out perfectly every time.)
If you’re using the withdrawal method in combination with another form of birth control, such as the pill or condoms, your chances of pregnancy are much lower. As Planned Parenthood explains, it’s still technically possible to get pregnant from pre-cum while on the pill, but it’s very, very rare — your chances are a fraction of a percentage point.