The golden ratio of nasal width to nasal bone length.

PURPOSE

To calculate the ratio of fetal nasal width over nasal bone length at 14-39 weeks' gestation in Caucasian women.

METHODS

Fetal nasal bone length and nasal width at 14-39 weeks' gestation were measured in 532 normal fetuses. The mean and standard deviations of fetal nasal bone length, nasal width and their ratio to one another were calculated in normal fetuses according to the gestational age to establish normal values.

RESULTS

A positive and linear correlation was detected between the nasal bone length and the gestational week, as between the nasal width and the gestational week. No linear growth pattern was found between the gestational week and the ratio of nasal width to nasal bone length, nearly equal to phi, throughout gestation.

CONCLUSION

The ratio of nasal width to nasal bone length, approximately equal to phi, can be calculated at 14-38 weeks' gestation. This might be useful in evaluating fetal abnormalities.