Fetal development in pregnancy week 6:embryo in second month This is going to be a busy week for your amazing little embryo. Their brain is still growing remarkably fast; miniature hand plates are starting to develop and the early formations of what will be their fingers are already visible. Also, the lower limbs do not develop quite as fast, so they’re pretty much still flippers. Up until this point, your baby has been very curled up with the head and tail in close proximity, but this week their trunk and neck are beginning to grow and straighten as their tail recedes into its resting position in the back. Even though your little miracle is only 6 weeks old, they’re already capable of demonstrating reflex responses to touch!