Scarleteen

I had a few questions about the lifespan of sperm and whether it can travel (be mobile/swim) outside of vagina and still be live -

How long can the sperms live in an ejaculate in an underwear? I had a wetdream. I only changed underwear after about 4 hours (i know the time because I checked time when I was briefly awake after wet dream and then slept back). When I changed underwear (took shower) I did see couple wet spots on the underwear, rest was dry. Does that mean there could have been live sperms in the underwear? I thought in 4 hours they should have all died.

I am asking the above because when I removed underwear, and it hit carpet, is there a chance of live sperm transferring from either my skin or underwear to the carpet/floor area in bathroom? My partner also changed clothes right after I did and had her underwear around the same spot where I changed. Therefore my next question. Is there a way sperm can transfer from floor/carpet to underwear? I mean can sperm move like that (similar to spilled drops of liquid transferring from floor to clothes)?

We won't engage with pregnancy scares as our policy.

That said, none of this is how human reproduction works -- for example, sperm cells can't move on their own in any circumstance -- and it sounds like you simply may not know how it does. Here's a piece that can give you that education clearly and in one fell swoop: Human Reproduction: A Seafarer's Guide.