I've learned first hand when they warn you against lying on your back during pregnancy it's a real concern.

We had our anatomy scan today and after about 45 mins I started feeling nauseous and dizzy and sweaty. I must have started to look like I wasn't okay because the tech asked if I was ok. I told the tech I needed to sit up for a minute. The student tech went to get me water and I asked my husband for the garbage pail. I thought I was going to puke. Next thing I know I'm dreaming and come back to being rolled on my side by the techs. My husbands face looked horrified when I finally came back. He said it was the scariest thing he's ever seen.

Apparently the weight of your uterus can push on your main blood vein blocking blood from getting back up to your heart.

Other than that excitement! Baby is growing well :)