Hello thanks for writing in to HCM. I will explain the abbreviations- AC- abdominal circumference, FL- femur length, BPD- biparietal diameter, HC- head circumference and they denote size of the abdomen & thigh bone respectively & last two the head size . These are fetal parameters measured during an ultrasound scan to calculate the gestational age and baby weight, All machines have an inbuilt software for calculations and commenting only on these measurements per se is not possible. Each of these parameters will correspond to a particular gestational age , and they must match each other individually and as a whole. It is more important to note if there has been adequate growth from scan to scan as well as other things like amount of amniotic fluid at this stage. I hope this has been helpful. Take care.