Week 20 of Pregnancy: What's Going On Inside

Topic Overview

By week 20, you've probably felt your baby move. It may not feel like an obvious kick-yet! Instead, your baby's first movements might feel like "butterflies" or gas bubbles.

Inside the uterus, your baby is enjoying some regular activities: thumb-sucking and opening and closing his or her eyes.

Wondering what your baby looks like now? As you enter your sixth month of pregnancy, your baby is now about the size of a banana. Average baby length is 160 mm (6.3 in.).

How your baby is changing

Here are some of the important facts and developments around 20 weeks.

• This is a time of very rapid growth, especially from 15 to 18 weeks of pregnancy.
• By now, the head is no longer so big compared to the rest of the body.
• You can see bones on ultrasound by the end of week 17.
• At this size, your fetus is still small enough to change position a lot-from head-down to feet-down, or even sideways.
• If this is your first pregnancy, you will start to feel your fetus move. The first flutters you feel are called "quickening."
• At the end of this month, the fetus starts building up body fat.