The fertilized egg cell will start the fission 24 hours after fertilization. It takes 5-7 days before the lump of cells has arrived in the uterus.
Once it has arrived in the uterus, the lump of cells will implant in the uterine wall. From this moment the fetus is called an embryo.
Hormones!
Immediately after fertilization, the HCG hormone, also known as the pregnancy hormone, is made, among other hormones. This hormone sees to the safe growth of the baby, but unfortunately also causes pregnancy complaints such as nausea and painful breasts.