Social and demographic factors such as mother’s age, education level and ethnicity can predict the likelihood of having an operative birth, according to new research based on the Millennium Cohort Study (MCS).
Researchers from the University of York analysed data from almost 19,000 mothers and babies from across the UK to see which women are at a greater risk of operative birth, such as a caesarean section or instrument-assisted vaginal birth.
The researchers found that age was a key factor in determining the mode of birth for all women, with operative birth rates rising with the age of women in the study. Fewer than one in ten first-time teenage mums required an emergency caesarean, compared to almost one in three mothers who were 35 or older when they had their first child.
Caesarean rates in the UK have increased since the 1980s, but there has been no associated decrease in instrumental vaginal births. Operative births can lead to longer hospital stays and poorer psychological wellbeing, as well as being costly to the NHS.
Some social and demographic factors had a different impact on first-time mothers than those who had already given birth to one or more children.
First-time mothers from lower occupational status households were 1.5 times more likely to have an instrumental vaginal birth and over twice as likely to have a planned caesarean.
For women who were already mothers, educational attainment was more predictive of mode of birth. Women with A-level qualifications were at a lower risk of having a planned caesarean than those who held a degree-level qualification.
The study also found that women’s migration status and ethnicity was likely to affect their mode of birth. Immigrant women who had lived in the UK for more than five years and were already mums were at a higher risk of emergency caesarean than those born in the UK.
First-time black mothers were less likely to have an instrumental vaginal birth than their white peers, and Pakistani and Bangladeshi women who were already mums were less likely to have a planned or emergency caesarean.
Dr Holly Essex, who led the research, suggests that these factors may explain the wide discrepancies in caesarean rates across England.
“In this country there are significant variations in rates of caesarean section between maternity units in different geographical areas, and this research goes to show that it could be due in part to the characteristics of the population they serve,” she said.
“Our study used individual-level rather than area-level measures of socio-economic status, and controlled for a larger range of factors than any other study of this type has been able to before.”
“Further research is needed to establish to what extent socio-demographic differences in mode of birth are a reflection of the attitudes and behaviours of women, or health professionals, or whether they reflect deeper health differences among these women.”
‘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’ by H. N. Essex, J. Green, H. Baston and K. E. Pickett was published in the British Journal of Obstetrics and Gynaecology in March 2013.