I was so excited for my 20-week ultrasound. I hadn’t seen the baby growing in my belly since my 12-week scan. But, here’s the thing: There’s a lot more to it than determining your baby’s gender. “The 20-week ultrasound is one of the most important doctor’s visits of the entire pregnancy,” says Anna Barbieri, MD, an ob-gyn in private practice in New York City. Here's a rundown of what to expect at your 20 week ultrasound.