What is the normal biparietal diameter at 39 weeks?
At 39 weeks, a fetal biparietal diameter of approximately 9.5 cm is considered normal.
The biparietal diameter refers to the widest distance between the two sides of the fetal head and is generally related to the baby's weight, gestational age, genetic factors, and individual head shape. It is commonly used to assess fetal growth and development. Normally, at 39 weeks, the average biparietal diameter is 9.08±0.59 cm. Therefore, if an ultrasound shows a biparietal diameter of around 9.5 cm at this stage, it falls within the normal range.
At 39 weeks, delivery is approaching. If the biparietal diameter exceeds the transverse diameter of the maternal pelvic outlet, it may affect vaginal delivery. Additionally, symptoms such as bloody show, pelvic pressure, lower abdominal discomfort, and abdominal pain could be signs of impending labor, and timely medical evaluation and hospital admission for delivery are recommended.