RESUMEN
BACKGROUND: The existing inconsistent association between the caesarean rate and maternal socio-economic status (SES) may be the result of a failure to examine the association across indications for caesarean. This study examined the variation in caesarean rates by maternal SES across diverse obstetric-indications. METHODS: Data on demographics, education, insurance status, medical-conditions, and obstetric characteristics needed to classify deliveries according to Robson's 10 obstetric-groups were extracted from the 2015 US birth certificate data (n = 3 988 733). Multivariable log-binomial regression was used to analyse the data adjusting for confounders. RESULTS: The caesarean rate was 34.1% for women with high SES and 26.8% for those with low SES. After adjustment for confounders, the rate was similar between women with graduate degrees and those who did not complete high school (relative risk (RR) 1.0, 95% confidence interval (CI) 0.9, 1.1). However, different rates of caesareans across SES were observed for particular obstetric-indications. Notably, women with graduate education compared to those who did not complete high school were more likely to have a caesarean (RR 3.0, 95% CI 2.9, 3.1) for a low-risk condition (group 1: nulliparous women with single, cephalic, ≥37 gestational weeks, and spontaneous labour). Women with private insurance were more likely to have a caesarean in almost all obstetric groups, compared to those without private insurance or Medicaid. CONCLUSION: Examining the overall caesarean rate obscures the relationship between SES and the use of caesarean for particular obstetric-indications. The unequal utilisation of caesareans across SES highlights overuse and potential underuse of the caesareans among American women.