What Is the Fetal Biparietal Diameter (BPD) Standard Reference Chart?
Aug 31, 2021
Source: Cainiu Health
Dr. Li Ying
Introduction
At 13 weeks’ gestation, the fetal biparietal diameter (BPD) is typically around 2.0 cm. Prior to 31 weeks, the BPD increases by approximately 3 mm per week; between 31 and 36 weeks, the weekly increase slows to about 1.5 mm. In a full-term fetus, the BPD generally ranges from 9.0 to 10.0 cm. A BPD exceeding 10.0 cm in a full-term fetus warrants consideration of fetal macrosomia.
The standard reference table for fetal biparietal diameter (BPD) lists the normal BPD values corresponding to different gestational ages. The fetal biparietal diameter refers to the maximum transverse diameter of the fetal head—also known as the fetal head’s greatest transverse diameter. Typically, a clearly defined fetal skull ring becomes visible on ultrasound only after 12 weeks’ gestation; therefore, BPD measurements are generally performed starting from week 12 onward.
At 13 weeks’ gestation, the fetal BPD is approximately 2.0 cm. Prior to 31 weeks, BPD increases by about 3 mm per week; between 31 and 36 weeks, the weekly increment slows to approximately 1.5 mm. In a full-term fetus, the BPD typically ranges from 9.0 to 10.0 cm. A BPD exceeding 10.0 cm in a full-term fetus raises suspicion of fetal macrosomia. Conversely, a BPD below 9.0 cm warrants evaluation for intrauterine growth restriction (IUGR).
