Pregnancy Calendar - Week 4
The embryo is hard at work this week making a placenta, umbilical cord and the basic beginnings of a body. The embryo is made up of three primitive layers which will evolve into every organ and tissue of your baby's body - the inner layer (endoderm), the middle layer (mesoderm), and the outer layer (ectoderm). At this point, the embryo is approximately 1mm long.
You have missed your first period this week and this is when major physical changes start occurring, which will continue throughout the next 36 weeks! Your heart is beating faster (up to 15 extra beats per minute) because you need more blood to flow to the embryo and other parts of your body (your breasts in particular... hence the tenderness...). Your cervix is also softening and changing colour.Pregnancy Calendar - Week 4