Normal value of cephalic index and craniotypes: a pilot sonographic cephalometric survey of pregnant women of Yoruba ethnic origin in Lagos, southwest Nigeria


  • CLETUS UCHE EZE University of Lagos, Lagos Nigeria
  • David Chinwendu Ene
  • Livinus Chibuzo Abonyi
  • David Oselumenosen Omiyi


Fetus, simple regression, Bland-Altman plot, craniometry


Background: Sonographic cephalometry is used to identify ethnic differences. Biparietal diameter (BPD) and occipito-frontal diameter (OFD) may be used to compute cephalic index (CI).

Methods: A sonographer measured the BPD and OFD in 200 pregnant women of Yoruba ethnic origin. The formula BPD/OFD x 100 was used to compute the CI. Mean CI was used to determine craniotypes. Coefficient of correlation, line graph, and the Bland-Altman plot, were used to determine the relationship between CI, BPD and OFD.

Results: Mean CI was 77.24 ± 3.88 mm. There was a statistically significant difference (p < 0.05) in mean CI between fetuses of Yoruba, Igbo and Indian ethnic origin. Correlation was significant between CI and BPD (r = 0.163; p = 0.02) and between CI and OFD (r = -0.02; p = 0. 000); 68.0% of fetuses had mesocephaly. The formula CI = 0.0371(BPD) + 74.656 and CI = 0.0035 (OFD) + 77.559 may be used to calculate CI on the basis of respective sonographically measured BPD and OFD.

Conclusion: While the skull appeared to have grown to its full length and breadth in the first trimester of pregnancy, a typical fetus of Yoruba ethnic origin in Lagos metropolis most likely would have a long and flat skull at birth. Even as ethnic differences appear to be a major factor in the development of cranial development in the population studied, a simple regression equation can be used to compute cephalic index and to correct atypical craniotypes among fetuses without craniofacial anomalies.

Author Biography

CLETUS UCHE EZE, University of Lagos, Lagos Nigeria

Lecture, Department of Radiation Biology, Radiotherapy, Radiodiagnosis and radiography, College of Medicine of the University of Lagos, Nigeria.






Original Articles