Standard Biparietal Diameter and Femur Length
Disease description:
I’m going to the hospital for my prenatal checkup tomorrow, so I’d like to first understand the standard measurements for fetal biparietal diameter (BPD) and femur length (FL).
Doctor's answer (1)
Dr. Zhang Lu
Under normal circumstances, the fetal biparietal diameter (BPD) and femur length (FL) typically differ by approximately 2 cm. Femur length measurement is generally initiated at 13 weeks’ gestation; as gestational age increases, FL progressively lengthens—thus, no fixed value exists.
Standard reference values for BPD and FL vary according to gestational age. For example, at 24 weeks’ gestation, the average BPD is 5.9 cm and FL is 4.4 cm; at 36 weeks, BPD averages 8.9 cm and FL 7.0 cm; and at 40 weeks, BPD averages 9.4 cm and FL 7.7 cm.
Since fetal growth rates and maternal nutritional status vary among individuals, these measurements serve only as general references.
