By Joanne Stone, Keith Eddleman, Mary Duenwald

During weeks 17 to 20, your baby begins to put on some fat and looks more like a real baby. The baby’s skeleton, which starts out mostly as cartilage, is now transforming into bone. Often you may notice a little fluttering sensation in your abdomen. This could be gas, but more likely it’s early fetal movement.

By 20 weeks, the top of the uterus (called the fundus) is at the level of your belly button. Twenty weeks is the halfway mark, so you should congratulate yourself. The second half usually flies by faster than the first.

You want to keep the following in mind:

  • Schedule your anatomy ultrasound. This is the ultrasound where the doctor is able to check the baby’s anatomy and make sure he is growing properly and is surrounded by normal amniotic fluid.

  • Pay attention to the baby’s movements. This period is when many women start to feel the baby move, which is called quickening. First-time moms, though, don’t always feel quickening this early, so don’t be alarmed if you haven’t.

Your baby now weighs about 10 ounces (300 g) and is about 10 inches (26 cm) long.