Head Circumference at Time of Birth: A Possible Predictor of Labour Outcome in Singleton Cephalic Deliveries at Term?

Background: Several studies have attempted to predict the outcome of labour in cephalic presentation using such parameters as maternal pelvic dimensions and estimated fetal weight. Though, the fetal head is widely recognised as the best 'pelvimeter', dimensions of the fetal head have been neglected for this purpose. The study was therefore aimed at determining any possible association between fetal head circumference at the time of birth and the route of delivery in parturient women.
Method: Hospital records of all term singleton cephalic deliveries between January and December 1999 at the University College Hospital, Ibadan were examined. Maternal characteristics such as age, parity and fetal characteristics such as gestational age at delivery, birth weight, Apgar scores and sex were recorded. The occipito-frontal circumference was measured in centimetres on the second day of life when caput and moulding would have subsided by the attending paediatric resident doctor as part of routine examination of the newborn. Relationship between head circumference and mode of delivery was studied by comparing women who had vaginal delivery with those who had caesarean section on account of dystocia in labour.
Results: While there was no significant difference in caeserean section rate in the the parous women, the rate in nullipara rose markedly from 13.3% with fetal head circumference of less than 37cm to 60.0% for measurements of 37cm and above.
Conclusion: Fetal head circumference may be useful in predicting the likely mode of delivery especially in the nullipara. Prospective studies using ultrasonically determined fetal head circumference at the time of labour are recommended to further substantiate the findings.