Big placenta, baby small, 20 weeks - help?

[confusedbyitall23]

Hello,
I hope someone has been in a similar situation. I'm so upset and scared. Last Thurs I had my 20 week scan and sonographer said baby head circumference and abdomin was measuring small, 3 percentile but that everything else looked fine. She referred us for a medical sonograph which happened today and Dr told me i have a large placenta and baby is measuring small. She offered us amniocentesis which we are getting this Thurs coming. They took blood from me incase it was an infection and then the thirdly she said that the placenta may eventually make the pregnancy not viable and I could miscarry. I'm so shocked. Scared and sad. Is this really unusual? Does anyone have a similar experience?
Thank you so much
X

Anyone? I'm so worried

Hi, I'm sorry you have been through this. I have a similar situation. My babys head is measuring on the 3rd percentile. The amnio came back fine but the scan at 24 weeks still showed the head on the 3rd percentile, so not growing in line with the body. Do you mind me asking what the outcome was for your baby. We are really concerned, will have another scan at 28 weeks and then might be referred for an mri scan. X