18 Weeks

Little One this week:

Size:
Baby is about 5 to 5 1/2 inches long from top to tail and weighs a little more than five ounces, about the size of a lobster tail.

Development:
While in earlier weeks, the baby may have been able to sense sound with it's primitive ear structures, this week, the bones of the ear become fully formed along with the part of it's brain that processes signals from it's ears.
There's still plenty of room in my uterus, so the fetus can be quite active with it's new muscles. Baby may change positions frequently, cross it's legs, recline, suck it's thumb, and turn somersaults.
The baby's retinas have become light sensitive, and the baby may be able to detect a glow if you shine bright lights at your belly (even though it's eyelids are sealed).