Week 17

Your baby is the size of an Onion

Your baby measures about 4.5 to 5 inches (11.4 to 12.7 cm) long from crown to rump. At this point your baby weighs about 3.5 ounces (99.2 grams).

The placenta, which nourishes the fetus with nutrients and oxygen and removes waste, is growing to accommodate your baby. It now contains thousands of blood vessels that bring nutrients and oxygen from your body to your baby's developing body.

Your baby starts to form fat under its skin this week. This fat is important in generating heat and maintaining a steady metabolism. At birth, 2 to 6 percent of your baby’s weight will be fat. This will help your baby maintain a steady body temperature outside the womb.

The baby’s movements are becoming stronger and more frequent. Loud noises outside the uterus may also startle the baby.