Yes, that's true. Mas okay kapag left side matutulog dahil sa blood flow, and it prevents din na magkaroon ng still birth. Para sa mga hindi sanay, well I guess kailangan sanayin ang sarili nila. Kasi it's for their own good and for their baby's welfare din naman. You can read this article https://ph.theasianparent.com/posisyon-sa-pagtulog-ng-buntis