Each month, women undergo the process of Ovulation. If a sperm fertilizes the egg released during ovulation, it will result in the formation of an embryo that will eventually get implanted on to the lining of the uterus and develop into a baby.
It will be useful to understand some basic facts about the time taken for fertilization.
After ejaculation, the sperms enter the female reproductive system where they compete for their chance to fertilize the egg. The sperm travels roughly about 15 to 18 cm where they seem to be competing against each other to reach the egg.
Once the sperm enters the reproductive system, it can take about 30-45 minutes to reach the egg. For this, it is important to have a healthy sperm which has the right kind of motility to reach the egg and fertilize it.
Once inside the body of a woman, a healthy sperm can live up to 2-5 days. Once the sperm reaches the released egg, it does not mean that it is capable of fertilizing it immediately. The sperm will then undergo a process called capacitation in the reproductive tract. This process will take about 10 hours.
It is safe to say that the fertilization time is appropriately about 24 hours. When the sperm penetrates the egg, the surface of the egg changes and blocks the entry of other sperms. The genetic makeup of the baby is complete at the moment of fertilization.
The fertilized egg then starts dividing frequently into many cells. Once the fertilization process is over, the fertilized egg will travel through the fallopian tube, enters the uterus in another 3-4 days, and attaches itself to the lining of the uterus, and slowly grow to become the baby.