31 weeks 5 days with a grade 3 placenta?

Anyone else have this? From my understanding it shouldn’t happen until 37-ish weeks. Baby is measuring bigger and doctor is saying I may need a c section due to how small I am and how big she may be.

I do not smoke and I do not have blood pressure issues. Doctor also didn’t mention the grade of my placenta, but me being curious I ran to google and looked it up and the results scared me.

I’m down to appointments being every 2 weeks now, but has anyone ever dealt with this?