Fertilization: Sperm Penetrates Egg. It takes about 24 hours for a sperm cell to fertilize an egg. When the sperm penetrates the egg, the surface of the egg changes so that no other sperm can enter. At the moment of fertilization, the baby's genetic makeup is complete, including whether it's a boy or girl.
Implantation bleeding is an early sign of pregnancy and only experienced by 1/3 of women. Discover when and what to look for as a sign of implantation. Implantation bleeding is an early sign of pregnancy and only experienced by 1/3 of women.
Your bleeding could last up to the six or seven days of implantation and therefore up to the when you expect your next period. This means if your menstrual cycle is the average 28 days long, your implantation bleeding could occur anywhere between day 20 or 21 up and days 26 to 28.