When trying to conceive it helps to understand how the male and female reproductive systems function.
Ovulation: Every month a female releases one mature egg from her ovaries. The egg leaves the ovarian follicle and travels to the end of the Fallopian tube. It then begins to move slowly down the Fallopian tube to the uterus (womb). For a pregnancy to occur the egg must be fertilised by male sperm while still in the Fallopian Tube.
Fertilisation can occur during the ‘fertile window’, which is five days before ovulation and the day of ovulation. By approximately 12 – 24 hours after ovulation, fertilisation can no longer take place during that menstrual cycle, as the egg is no longer in the Fallopian tube.
Only the best sperm reaches the Fallopian tube during/after intercourse. While many of these sperm manage to bind to the shell, the sperm needs to break through the egg’s shell to fertilise the egg. If a sperm manages to break through the shell, the sperm -and egg’s genetic material (male- and female pronuclei) move towards the centre of the egg. Embryo development then starts to take place through cell division.
Around day 4 – 6 of cell division, the blastocyst stage occurs (the embryo fills with fluid creating a cavity, outer cells start forming a wall and inner cells start forming a ball). At the blastocyst stage the embryo enters the womb. Over the next few days it will hatch out of its shell and bury into the womb. It will grow and develop blood vessel connections with the mother. This stage is called implantation. By the stage of implantation, the embryo sends out chemicals into the mother’s blood stream, which will be picked up by a pregnancy test about two weeks after fertilisation. The embryo then continues to grow and develop into a baby.