Which women are at an increased risk of a caesarean section or an instrumental vaginal birth in the UK: an exploration within the Millennium Cohort Study

Objective To explore the maternal demographic factors associated with operative births (instrumental vaginal births or caesarean section), after adjustment for health, interpersonal, pregnancy, labour and infant covariates. Design Nationally representative cohort study. Setting Women giving birth in the UK, during the period 20002002. Sample A total of 18239 motherinfant pairs. Methods Multinomial logistic regression models were estimated to explore the relationship between demographic characteristics and mode of birth, stratified by parity. Main outcome measures Self-reported mode of birth, defined as unassisted vaginal birth, instrumental vaginal birth, emergency caesarean section and planned caesarean section. Results For primiparous women, operative births rose steeply with increasing maternal age. Women from lower occupational status households were at an increased risk of planned caesarean section. Mode of birth differed significantly by ethnicity. For multiparous women, a younger age at first birth was protective of a later caesarean section or instrumental vaginal birth at the cohort birth. Women with qualifications normally taken at the age 18years were at an increased risk of planned caesarean section compared with women with degree-level qualifications. Mode of birth differed significantly by ethnicity, and non-UK born women were at an increased risk of emergency caesarean section. Conclusions The sociodemographic characteristics of UK women independently predict mode of birth. Further research is needed to establish to what extent sociodemographic differences in mode of birth are a reflection of the attitudes and behaviours of women, or health professionals, and are therefore amenable to change.