Correlation of fetal age and measurements between 10 and 26 weeks of gestation.

Fetal measurements, especially fetal foot length, were correlated with fetal age--as measured by last menstrual dates--for 1800 tissue specimens obtained after dilatation and evacuation abortion. These observations were compared with Streeter's results from 1920. Fetal ages ranged from ten through 26 completed menstrual weeks. Fetal measurements including weight, knee-to-heel length, biparietal diameter, placental weight, and amniotic fluid volume were correlated with foot length. Sonographic biparietal diameter obtained by real-time imaging was correlated with tissue measurement of biparietal diameter for various fetal ages. The difficulties of establishing valid correlations are discussed, and a table of recommended values for fetal measurements by week of fetal age is provided.