Retroplacental Haematoma Question

I had a retroplacental haematoma when I was pregnant with #1, and it was picked up at 19 weeks when I had some serious cramping and was sent for an ultrasound.
I was told to go home and observe strick bed rest. I didn't do that.
At 20 weeks I get severe cramps, doubling me over and I go to the ED to be told I am miscarrying/preterm labouring. I am told to expect to deliver stillborn, foetus isn't viable blah blah blah. Put on a drip kept in bed for 3 days and told to go home and rest as much as possible.
17 weeks later I have a healthy baby boy weighing nearly 4kg by caesarean section.

Now, why would you need bed rest for a haematoma? If it's abrupted surely doing normal stuff isn't going to affect it??
As it turned out I was diagnosed with mild PE at 24 weeks and told to go on bed rest again... then had it forced upon me. Could the haematoma have had anything to do with the PE? Seeing as there were already placental implantation issues, and that has been linked to PE.

Also, the fact that I had a haematoma from abruption was listed as one of the compunding reasons that I needed a caesarean, and that a vaginal deliveryy was not preferable.
I thought it had healed over, so what should it matter?

I am pregnant with #3 (pregnancy #2 had it's own dramas) and I am doing some emotional unpacking and want to figure this out.

Thanks in advance