At week 16, 14 weeks since conception, your fetus measures about 4.5" (12 cm) in length, about the size of an avocado, and weighs almost 4 oz (110 g). The fetus has grown numerous bones at this point, many of them still unconnected. Bones will go on lengthening and ossifying (hardening) throughout your pregnancy. At birth, they will have ossified enough to support your baby's body, but it will be another year or more before complex joint mechanisms tie them all together so that she has enough strength and flexibility to toddle.

Movements, like kicking the legs and extending the arms, are more coordinated this week—and there are lots of them, too, although it’s still too early for you to feel them. Your fetus has started to move her eyes, although they are still sealed shut. And the little one has developed a new, important skill: she can now grasp with her fist, thanks to her opposable thumb, a feature we share with other primates.