Amniotic fluid is beginning to accumulate around this ball of cells, and it has implanted in the uterus. There is even a very primal system that handles circulation and nutrition – a task that will soon be taken over, typically within the next week or so, by the placenta.

Your little blastocyst is multiplying rapidly, and becoming an embryo that is going to implant in your uterus this week. Part of this group of cells is going to become the placenta, and the other part is going to begin to become your baby. Your body will begin to produce hCG (human chorionic gonadotropin) – the pregnancy hormone. This hormone tells your body to stop releasing other eggs and increases levels of the hormones estrogen and progesterone that keep your uterus from shedding its lining. You may notice your breasts feel very tender and look a bit swollen, and you feel exhausted for no reason. Maybe you’ve even noticed a bit of spotting, known as implantation bleeding. This is almost time to take a home pregnancy test. Don’t worry if it comes back negative; take another in a few days when the hCG levels may be higher.