Introduction
Globally, the proportion of births which occur by caesarean delivery is
increasing1 but the underlying drivers are poorly
understood. Several attempts have been made to assess how temporal
changes in individual maternal characteristics, obstetric practice, and
maternal request for caesarean delivery have influenced this
trend.2–5 Large observational studies in the United
States have found that changes in maternal risk profile over time do not
explain all the observed increases in caesarean rates, but these studies
did not account for some factors such as age or body mass index
(BMI).5,6 Others have reported that maternal BMI alone
explains 9% to 14% of caesarean deliveries.2,7,8
In an Australian setting, the most common indications associated with
recent increases in caesarean deliveries were previous caesarean
delivery, slow progress in labour, and breech
presentation.9 Additionally, the importance of primary
caesarean delivery has been emphasized because it leads to planned
repeat caesarean deliveries.10 However, we do not know
how much of the overall rising caesarean delivery rate is being driven
by overall temporal changes in maternal characteristics.
By understanding the underlying drivers of increases in rates of
caesarean section, clinicians and health systems can better explore safe
preventative measures. This is important because primary caesarean
deliveries can increase morbidity and mortality, increase risks in
future pregnancies, and many women would choose to avoid caesarean
delivery if safe to do so.11,12
The aims of this study were to assess the contribution of demographic
and clinical factors to changes in the caesarean delivery rate during
the time when it increased from less than 20% to more than 30% of all
births.