This was noted at my 20 week scan (it was the very last thing they checked and everything else is fine). My own blood pressure has been fine all the way through but apparently the blood is struggling a bit to get to the placenta. I'm already on low dose aspirin, which is the usual solution. I have a rescan at 28 weeks to make sure the baby is still growing well. It apparently gives you a fairly high chance of developing pre-eclampsia and a risk of slow growth for the baby.
I wondered if anyone else has had this and how things are going or how they turned out?