What about pre ejaculate and sperm...?

[andvr]

Hello! I'm new here and I'm loving it. I wanted to start asking you guys a question that I always have had.

I know that usually pre ejaculate does not contain sperm, and If it does, it's because of a previous ejaculation.
Now I've been wondering... how even sperm can live in the pre ejaculate fluids and get to an egg if it does not has all the fluids that are present in a full ejaculation?? I know semen it's a mix of many fluids that "work together" trying to keep sperm alive, giving them a lot of properties like protein, fructose, etc.

So, I'm also thinking, sperm can live inside a woman's body to 3 - 5 days, right? I'm guessing this is because they're being "protected" by the semen... what about the sperm present in the pre ejaculate then? do they last the same amount of time inside a woman's body?

I don't know if it's a stupid question haha, I'm very curious about it

[Heather]

Ultimately, you're asking a question we can't answer, because, to my knowledge, study has not been done on trace sperm cells carried by pre-ejaculate, specifically, and the amount of time they can potentially hang around in the vagina or cervix. Most study done on fertility and human reproduction is done with optimal conditions for reproduction -- so, a full ejaculation and someone ovulating -- since it really isn't useful to know about controllable conditions where reproduction isn't likely or as likely.

Understand that withdrawal is estimated to be around 96% effective in perfect use, and that includes the presence of pre-ejaculate. That means, if that estimate is correct, that, at most, there is only a 4% chance in one year of trace sperm cells in pre-ejaculate resulting in pregnancy. You can perhaps see then, that while that's not impossible, it's very unlikely, so from a practical standpoint of both contraception (especially given how many studied and accessible methods of contraception we have that work much better than withdrawal does) and fertility, people just aren't at all likely to try and study this much or gather this kind of data.