Must I always sleep on my left during pregnancy?

Doctors and midwives always recommend sleeping on your sides (left preferably). Lying on the right side was a little more comfortable. Sometimes I do lie on my back with my leg on a pillow. I think the most important thing is to be comfortable. It is also not good to be in the same position for long periods, but I don't think most of us will remain in the same position throughout the night.

Its ok not to sleep on your left for first and second trimester. My gyane told me as long as i feel comfortable enough. I guess its more important to sleep on your left on your third trimester.

Only for the last trimester, yes. Avoid sleeping on your back as it risks of stillbirth

In my early second tri now, and I found it more comfortable to be lying on my left.

Sleeping on your back increases the risk of stillbirth. Sleep on your sides better.

I usually switch between my left & right sides before/during/after pregnancy

You can sleep right side but its better sleep on left during pregnancy..