Conception occurred. Not already guessed what was going on — but the development of the unborn child has already begun. However, your body also noticed the importance of the event and "broke the alarm" of the immune system. At the first cell division fertilized egg in the body begin producing factor providing immunological protection of the fetus (and immunosuppressive proteins, etc.). Without them, the mother's organism could consider the future of a child with a foreign body and start a fight with him.
In addition, at the end of this week begins to produce the pregnancy hormone — hCG (human chorionic gonadotropin). Soon this hormone would be sufficient to test for pregnancy confirmed your suspicions: you become a mother.
The sperm united with the egg. The result was a "big" (smaller than a grain of salt) cell that contains 46 chromosomes inherited from parents (23 chromosomes from each). Fertilized egg carries all the genetic information about the future of human sex, color of eyes and skin, facial features, etc.
The zygote (fertilized egg) Begins to divide, while moving through the fallopian tube toward the uterus. By the third week comes the big moment — implantation — the introduction of the embryo in the uterine wall. If all goes well, the responsibility for his livelihood will assume future mom.