Sperm only live up to a maximum of three days. But they also have to REACH the egg which they can do within an hour. Therefore fertilisation could happen in one hour after sex, or if you had sex yesterday, the sperm could be lying in wait for the egg to come to them!
Fertilization
Because the triploid endosperm nucleus is formed at the same time as fertilization and then it develops.
Fertilization
7 hours
21 days
Conception is the moment of fertilization.
20 billion years
Fourteen days after intercourse.
More than an average human
About 10 days.
The menstrual cycle typically lasts 28 days - but everyone's cycle is different. If fertilization does take place then there is no menstrual cycle, this would continue into pregnancy.
for reptiles it is internal fertilization and they can't do external fertilization