Yes, a Doppler scan woul due able to tell the condition of the placenta. It measures the blood flow through the placenta between mother and baby (iirc). Your age can also play a part, for example, over 40 you should be induced on your due date.
Unfortunately, I have spoken to many mothers who went overdue whose babies were stillborn because their placenta stopped functioning properly.
My first baby was born prematurely (25w) due to a cord prolapse, unfortunately, I saw her heart stop during a scan to see whether I needed a crash section or not. She was born vaginally.
I really wanted a good vaginal birth, it wasn't going to be a home birth, fine, but a nice birth centre home birth. Ended up having an emergency section for dd2 due to fetal distress. My placenta wasn't functioning well, I had high resistance at the uterine artery and was on aspirin. I didn't want to go past my due date. I was petrified of another stillborn baby - I couldn't have gone through that again...
So dc3 I really hoped to vbac. I had placenta Previa, a decision was to be made at 36 weeks when they performed a scan. At the scan, a major vein was 3cm away from my cervix. They couldn't tell who vein it was, but if it was the baby's, it could have contained a large amount of her blood supply. They recommended a section. I was truly gutted, I really wanted to right having to labour with my daughter, I wanted a screaming, healthy baby at the end of a birth. But I couldn't risk losing another baby, so a section it was.
Consequently, dc 4&5 were also sections...
Now upon reflection, with my youngest dc at 2yo, it doesn't matter how they are born, just that they are here safely. No one asks how my dcs were born! Either way, I did bear them, but thoughout the journey I did feel their was pressure to have a baby vaginally. A registrar tried to tell me to go far a vaginal birth after 2 sections! Now I know people do, but with my obstetric history?!?
I know that this is different from others, but I'd just go for the way that results in the safest delivery for your child.