The relationship between gestational age and the incidence of classical Caesarean section

Improved neonatal survival has led to a rise in the number of Caesarean sections being performed in the presence of extreme prematurity. Many of these operations require an incision in the upper uterine segment with consequent ramifications for the management of any subsequent pregnancy. In this analysis of obstetric patients in a tertiary referral institution over a 9-year period, there was an overall Caesarean section rate of 18%. A classical incision was performed in 1% of all Caesarean sections, but at 24 weeks' gestation, 20% of Caesarean sections were 'classical'. This frequency decreased to less than 5% at 30 weeks and less than 1% from 34 weeks' gestation. Most women having a classical Caesarean section at term had either a transverse lie or a major degree of placenta praevia.