short femur length as a marker for downs syndrome

nina36

I am 19.2 days pregnant with my third girl. I had a level 2 ultrasound done on Monday and everything was good except for a short femer length. It was 26mm which apparently is lagging a week and a couple of days behind. The BPD is normal at 4.4 cm or 44 mm. All other markers were OK. I am 36 years old so my agen related risk is 1 in 137 for Downs and my sequential screen came back with a decreased risk of 1 in 800. I am 5 foot 2 with short legs and both of my other children are also short. Doctor told me that there is a 99+ % that everything is okay and a 1% chance that it is Down's. I don't know whether to have the amnio or not as there is a risk for miscarriage. HELP!!!!short femur length as a marker for downs syndrome