My husband and I just went for a prenatal check-up and the results are as follows: 19 weeks and 2 days pregnant, fetal heart rate 146 beats/minute, biparietal diameter 43mm (45%), head circumference 157mm (15%), femur length 28mm (24%), abdominal circumference 125mm (14%), posterior placenta position group 2, maturity level 0. So I would like to ask the doctor if these parameters are good and please explain to me what the percentile index in the ultrasound result indicates? I sincerely thank you!