Hello, I am 29 weeks,pregnant. Went for a scan today. Baby weighs 2lbs 2oz abdominal scan and brain scan are both normal however femur length is below the 5th percentile. They said the babies weight, head circumference and abdominal,growth are all normal so they are unsure about the femur. I have to go for a second scan next week to look at liquid levels and Doppler of the cord. What could cause this short femur lenght?