The proportion of twins born by caesarean delivery in Victoria increased threefold, from 24% to 71% of all twin births, during 1983–2015, despite high-level evidence that routine caesarean delivery of twins does not benefit mothers or babies, according to the authors of research published online today by the Medical Journal of Australia.
Researchers from Monash University and Monash Health, Mercy Hospital for Women, and Safer Care Victoria, analysed data from all twin births in Victoria between 1 January 1983 and 31 December 2015.
During that period, 32 187 twin pregnancies ended in live or stillbirths in Victoria. The proportion of twins born by caesarean delivery increased from 24% (156 twin deliveries) in 1983 to 71% (782 deliveries) in 2015. The proportion of twin births by planned caesarean delivery with twin pregnancy as the sole indication for caesarean delivery increased across this period from 1.8% (12 twin deliveries) to 21% (231 deliveries).
"Given high level evidence that routine caesarean delivery of twins does not benefit mothers or babies, and the recent suggestion that vaginal birth may actually be preferable, the mode of birth in uncomplicated twin pregnancies should be considered carefully," wrote the authors, led by Professor Euan Wallace, CEO of Safer Care Victoria and professor of Obstetrics and Gynaecology at Monash University.
"The rate of increase in the proportion of twin births by caesarean delivery was steepest during 1983–2003, with no significant change since 2004.
"The proportion of women with twin pregnancies who were aged 35 years or more increased from 15.4% (2007 mothers) during 1983–1998 to 32.6% (2560 mothers) during 2009–2015," they wrote.
"This change [in the proportion of twin caesarean deliveries] appears linked with the rises in the proportions of all twin births and of twin caesarean deliveries for which the twin pregnancy was the sole indication for caesarean delivery; these rises applied to both younger (under 35 years) and older mothers and to both nulliparous and parous women.
"The increased proportion of twins born by caesarean delivery in Victoria mirrors trends in other parts of Australia and overseas.
"The increase in the proportion of twins born by caesarean delivery has been accompanied by a marked rise in the proportion of such deliveries with twin pregnancy as the reason for surgery; removing interventions with this factor as the main indication would reduce the twin caesarean delivery proportion in Victoria to 40–50%.
"Twin pregnancies are more common in older women, in women with a high body mass index, and in women conceiving with assisted reproduction support, and these women and their obstetricians might prefer caesarean delivery if vaginal birth is regarded as more risky. However, vaginal delivery of twins is not less safe than a planned caesarean delivery, although high level evidence has only recently been reported," Wallace and colleagues wrote.
"The preference for caesarean delivery of twins may also reflect changes in clinician training, skills, and confidence with vaginal twin births; clinicians with limited experience are more likely to prefer caesarean to vaginal deliveries. If women are to make meaningful choices about how their children are born, a skilled specialist workforce must be maintained.
"But, as fewer than one-third of twins are now born by vaginal delivery, the opportunity for obstetric trainees to become proficient in twin vaginal births is much more limited than it once was."
The authors also found regional differences in their results. In Gippsland, the Victorian health region with the lowest rate of caesarean delivery of twins during 2010–2013 (100 of 187 deliveries, 54%), the proportion of caesarean twin deliveries with twin pregnancy as the sole indication was also relatively low (31 of 100 caesarean deliveries, 31%).
After adjusting for potential confounders, the odds of caesarean delivery of twins were lower than those for the reference region (North and West Metro) in the Gippsland, Eastern Metropolitan, Hume, and Southern Metropolitan regions, and non-significantly higher in the Barwon–South Western region.
"Our findings are probably generalisable, and therefore have implications for women, their babies, and obstetric practice across Australia," Wallace and colleagues concluded.
"We should ensure that we have a skilled and competent workforce to enable women to have a real choice in how their babies are born."
More information: Yizhen (Amy) Liu et al. Changes in the modes of twin birth in Victoria, 1983–2015, Medical Journal of Australia (2019). DOI: 10.5694/mja2.50402
Journal information: Medical Journal of Australia
Provided by Monash University