Left side lying?

Yes, you are correct. The left side is preferred due helping circulation thru the liver and keeping fetal weight off the aorta and inferior vena cava.

Seems a shame for her to quit school- there's no evidence to support bedrest as beneficial in preventing pre-term delivery. It would be best for all involved if some way was found for mom to continue to attend school as that will benefit the family long term.

Barring that the left side is still advocate as it improves blood flow as a previous poster mentioned.

She will not be able to tolerate lying on her left side all the time. Either side is fine, so is semi reclining. She will need to change positions frequently for her comfort (and sanity). Just avoid lying flat on her back. How much is she allowed to be up? If it's strict bedrest, I tell my patients they may take one shower a day and get up only to go to the bathroom. Most docs will OK going to the living room and reclining on the sofa instead of remaining in bed all day. Depending on the home situation, sometimes they have to keep a cooler by the couch to keep lunch and snacks and fluids so they don't have to get up to prepare their own meals. I also advise them to get a 32 oz insulated mug, fill it with water and sip on it constantly through out the day. Drink everytime there's a commercial on TV. She will need to drink at least 3 of them a day.

Is there any way she can keep up with some of her classes at home? She'll have lots of time for study if she can work out something with her teacher.

It's true that bedrest has never been proven to prevent preterm delivery, but it's never been proven not to help either. No one is going to do a study to prove it works either because no one would want to be in the control group.