Originally Posted by
atomic sagebrush
I know, I so wish they would come up with some technology that we could use to tell us for sure when we ovulated! But alas all we have are OPK, which are not that great, unfortunately.
Yes I can explain about the sperm. Some sperm are really fast and get to the egg almost right away, but then they all die. Scientists don't know the purpose of those sperm. Then more sperm will come to the egg over the course of time (within a few hours) but most of them are dormant, they are sleeping and can't fertilize an egg. They have to "capacitate" which means they have a protective cap that feeds them while they are asleep and keeps them alive longer, because once they capacitate, they die very quickly. This process of capacitation is puzzling because some sperm will capacitate in about 4 hours, but many others stay dormant longer. So there are always some sperm awake and some sperm asleep, until they all die, because that way there are always some sperm waiting and ready to fertilize the egg.
The "24 hour" idea causes a lot of trouble and confusion for people. Some people say that after ovulation you have 24 hours for the sperm to fertilize the egg. But this is not the case. 24 hours is a hypothetical number, that is based on an imaginary amount of time for the egg to survive after ovulation, for people to use when they are trying to avoid pregnancy. It is all but certain that eggs do NOT live 24 hours, possibly only as little as 8-12 hours, and that they are not able to be fertilized even less than that. The reason we say "24 hours", again, is for people who don't want to get pregnant, so they can avoid having sex on days they could be fertile. So it's meant to be a conservative, imaginary amount of time that an egg could theoretically survive so they do not have sex in that time frame and can't conceive. It was never meant to be any kind of guideline for people who are trying to get pregnant at all and it's a number that I wish everyone would forget about! You need sperm waiting for the egg BEFORE ovulation because it needs to capacitate and be waiting when the egg arrives. We can't wait until ovulation occurs, then have sex, then the sperm has to capacitate, and then hope the egg lives that long!!! It is a bad idea based on a misunderstanding of the "24 hour" suggestion.
The 7 day idea is a hypothetical amount of time sperm might possibly be able to stay alive in your reproductive tract. Some scientists have claimed they retrieved living sperm 7 days after intercourse from the Fallopian tubes. But we don't know for sure if this is even true (who knows if the couples in question really went 7 days or not!) and we also do not know if those sperm were able to fertilize an egg (they probably were not.) Studies have found that conceiving from sex anything more than 3 days before ovulation was unlikely, and the further you go, the more unlikely it is. 7 days before ovulation has like a one in a million chance of conception (if that, even - it may be impossible and then the handful of people who say this happened to them, ovulated sooner than they thought or had a birth control failure they are discounting). So it's one of those things you read online sometimes but again, it's really meant as more of a warning for people who are trying to prevent pregnancy and was never meant in any way as advice for people trying to conceive.