A momentous meeting has taken place inside you — a single sperm has broken through the tough outer membrane of your egg and fertilized it.
Several days after conception, the fertilized egg burrowed into the lining of your uterus and started to grow. A baby is in the making! You probably don't know you're pregnant yet, but you may notice a little spotting by the end of this week. This so-called "implantation spotting" may be caused by the egg burrowing into the blood-rich uterine lining (a process that began last week at 6 days after fertilization), but no one knows for sure. In any case, the spotting is very light and only a minority of pregnant women experience it at all.
