As soon as a mature egg is released from one of your ovaries during ovulation, it starts traveling from the ovary to your uterus through a very fine tunnel called the fallopian tube.
In order for conception to occur, the egg must meet a sperm cell inside the fallopian tube and be fertilized within 24 hours after ovulation, or it dies and your chances of conception are gone for that cycle.
Fortunately, sperm cells can survive inside your uterus and fallopian tubes for a couple of days, even up to five days if the conditions are ideal.
To optimize your chances of getting pregnant, you should make sure that a good supply of live sperm is ready to fertilize the egg once you ovulate.
A new life begins
When a sperm cell penetrates the egg cell and fertilizes it, the genetic material of the two cells combine to create a new cell—the beginning of a new human being.
If the sperm cell was male (a Y sperm), your baby will be a boy; if it was female (an X sperm), you will have a little girl. At this magical moment, your baby’s genetic structure is already complete, including eye color, adult height and everything else that will make up that unique new person.
The new cell rapidly starts dividing itself, multiplying new cells into a cluster called the blastocyst. The blastocyst continues travelling down the fallopian tube towards the uterus, a journey which takes between four and ten days. You are not actually pregnant until the blastocyst has implanted in your uterus, where it becomes an embryo and then, after nine weeks, a foetus.
Upon implantation, the embryo starts producing a hormone known as hCG (human chorionic gonadotropin). hCG stimulates the secretion of another hormone, progesterone, which enriches the uterine lining so that it can sustain the growing embryo instead of being shed during your period as it would in a non-conception cycle. hCG is also the hormone that is detected by pregnancy tests.