Secular trends in caesarean section rates over 20 years in a regional obstetric unit in Hong Kong

Introduction: Although caesarean section rates have been increasing over the years in both public and private sectors in Hong Kong, there has been a paucity of formal surveys on local trends in such rates. This study aimed to examine the trends in caesarean section rates over a 20-year period at a public regional obstetric unit in Hong Kong using the Robson's Ten-group Classification System. Methods: All deliveries in a single obstetric unit during a 20-year period (1995-2014) were classified into 10 subgroups according to the Robson's classification. The annual caesarean section rate for each subgroup was calculated and then stratified into 5-year intervals to analyse any significant trends. Results: The caesarean section rates in a total of 86262 births with complete data were analysed. The overall caesarean section rate increased modestly from 15.4% to 24.6% during the study period. There was an obvious increasing trend for caesarean section in those with previous caesarean section (Robson's category 5), breech presentation at delivery (category 6 and 7), multiple pregnancy (category 8), and preterm labour (category 10). A gradual fall in caesarean section rate from 14.4% to 10.8% was seen in primiparous women with term spontaneous labour (category 1). Statistically significant differences (P < 0.001) in these trends were confirmed when the data were stratified into 5-year intervals for comparison. Conclusion: The rising caesarean section rate may be associated with clinical management policies that allow women with relative risk factors (such as breech, previous caesarean section, or multiple pregnancy) to opt for caesarean section. This rise was counterbalanced by a decrease in primary caesarean section rate in primiparous women with spontaneous labour. The trend for caesarean section was more in line with patient expectations rather than evidence-based practice.