Which sperm cell fertilizes the egg when you have sex a few days before ovulation and which one fertilizes it during ovulation?
If you are referring to sperm with X or Y chromosomes, either one can fertilize an egg at any time there is an egg available to fertilize. That’s why no one knows whether they will be creating a female or a male fetus – it’s up to chance!
Debby Herbenick, PhD is an Associate Professor at Indiana University’s School of Public Health and a Research Fellow and sexual health educator at The Kinsey Institute. She’s the author of six books about sex; her newest is The Coregasm Workout. Follow Kinsey Confidential on Twitter @KinseyCon & visit us online at www.KinseyConfidential.org