14 weeks

This week's big developments: Your babies can now squint, frown, grimace, pee, and possibly suck their thumbs! Thanks to brain impulses, their facial muscles are getting a workout as their tiny features form one expression after another. Their kidneys are producing urine, which they release into the amniotic fluid around them— a process they'll keep up until birth. They can grasp, too.

In other news: Your baby's stretching out. From head to bottom, they measure 3 1/2 inches — about the size of a lemon — and they weigh 1 1/2 ounces. Their bodies are growing faster than their heads, which now sits upon a more distinct neck. By the end of this week, their arms will have grown to a length that's in proportion to the rest of their bodies. (their legs still have some lengthening to do.) They're starting to develop an ultra-fine, downy covering of hair, called lanugo, all over the body. Your baby's liver starts making bile this week — a sign that it's doing its job right — and their spleens start helping in the production of red blood cells. Though you can't feel their tiny punches and kicks yet, your little pugilist's hands and feet (which now measure about 1/2 inch long) are more flexible and active.