Hi mama! High-lying placenta just means it's positioned higher up in your uterus, away from the cervix, which is actually a good thing kasi lower placenta ang mas risky, so you're good! Grade 2 refers to the placenta's maturity level at 21 weeks, which is totally normal for your stage of pregnancy, so wag mag-alala. One of my mum friends had the same thing and her doctor said as long as it stays high-lying, walang problema with normal delivery, so she delivered vaginally no problem. I'd still ask your OB to confirm kung ilan pang weeks need mo i-monitor, pero based sa description na yan, it's a pretty reassuring finding!