I have seen many babies born ROA. It definitely isn't something that is a given - sometimes there are reasons why babies are ROA - esp if the placenta is on the front of the uterus and on the left side!
I wuld think that if you're a first time mom, just maintaining good posture (no knees higher than your hips) is all you need. Chances are, your baby will settle down in the best position for him/her.