Ultrasonic assessment of fetal growth.

Consecutive ultrasonic measurement of fetal biparietal diameter (B.P.D.) and fetal chest area was carried out in 152 normal and 59 complicated pregnancies between 25 and 40 weeks of gestation. In normal pregnancy the mean fetal head area (B.P.D.2) varied from 45.0 cm2 at 25 weeks to 98.0 cm2 at 40 weeks. The mean chest area varied from 31.3 cm2 at 25 weeks to 94.3 cm2 at 41 weeks. A normal curve of the head-to-chest relation was constructed. In the group of complicated pregnancies, two types of fetal growth retardation could be recognized. The first type was characterized by a normal head-to-chest relationship (symmetric type), the second type was characterized by an abnormal head-to-chest relationship (asymmetric type; relatively large head area). During fetal growth acceleration head-to-chest-relationship was abnormal (relatively large chest area).