Normal Biparietal Diameter at 34 Weeks of Pregnancy

At 34 weeks of gestation, the fetus has entered the late stage of development. At this point, measuring the fetal biparietal diameter (BPD) becomes especially important. A normal BPD generally facilitates vaginal delivery; however, if the BPD is excessively large, preparation for cesarean delivery may be necessary. So, what is the normal BPD value at 34 weeks’ gestation?

Normal Biparietal Diameter at 34 Weeks’ Gestation

The normal BPD range at 34 weeks is 84–93 mm. If the fetal head appears small at this stage, assessment of head circumference (HC) is also essential. A normal HC generally indicates appropriate fetal growth and development. Therefore, in addition to evaluating BPD, it is recommended to assess HC at 34 weeks. Pregnant women are advised to monitor fetal movements three times daily—morning, afternoon, and evening—starting at 34 weeks. When counting movements, a normal range is 3–5 movements within one hour, counted continuously over five minutes. Both excessive and reduced fetal movement may indicate fetal hypoxia.

The fetal biparietal diameter can be measured via ultrasound. As gestational age advances, the fetal skull gradually enlarges. For accurate BPD measurement, the distance should be taken from the inner margin of the skull on one side to the outer margin on the opposite side. Variations in equipment, operator technique, and institutional protocols may lead to slight discrepancies in measurements. An abnormally large BPD at 34 weeks warrants initial consideration of hydrocephalus. Therefore, during routine obstetric ultrasound, detailed evaluation of the fetal brain is recommended to rule out structural abnormalities or developmental anomalies.

Pregnant women are advised to maintain regular daily routines and balanced nutrition, with emphasis on high-protein foods, and to attend scheduled prenatal check-ups. We hope this information is helpful!