A large observational study published in JAMA this week found a small increase in asthma risk with planned C-section delivery compared to vaginal delivery. Here’s what the experts had to say about the findings.
Professor Jonathan Morris is Professor of Obstetrics and Gynaecology at the University of Sydney and Director of the Kolling Institute of Medical Research
“This paper confirms other reports that caesarean is associated with asthma. The association with planned caesarean does not agree with others that have explored this question. The findings are associative only and certainly should not be interpreted that caesarean causes asthma. However, for many reasons it is always wise to consider the risks and benefits of caesarean over planned normal birth.”
Commenting on the asthma aspect) Prof Seif Shaheen, Clinical Professor of Respiratory Epidemiology, Queen Mary University of London (QMUL), said:
“Many epidemiological studies have investigated a link between caesarean section and childhood asthma, but the evidence has been conflicting. This latest data-linkage study from Scotland, which is very large, reports an increased risk of asthma associated with planned C-section delivery, compared with vaginal delivery. I am puzzled why they did not also report results comparing unscheduled C-section delivery versus vaginal delivery. There are two key questions to consider in interpreting these findings:
“1. Is this association likely to be causal? In my view there are a number of reasons to doubt this interpretation: First, a key potential confounder*, namely maternal body mass index (BMI), was not controlled for in the analyses – women having a C-section had a higher BMI than women delivering vaginally (see Table 1), and a higher maternal BMI in pregnancy is associated with an increased risk of asthma in the offspring. Second, when the analysis was restricted to women with no missing data on potential confounders, planned C-section was no longer associated with an increased risk of hospital admission for asthma. Third, two Swedish studies, which used a more sophisticated methodology to rule out potential confounding, found no evidence of association between planned C-section and asthma in children over five years of age.
“2. Even if the link between planned C-section and asthma is causal, is it important and should pregnant women be concerned? As the magnitude of increased risk was small, and the proportion of women in this study having a planned C-section was also small (less than 4%), this means that the proportion of asthma in the population that might be attributable to planned C-section (assuming a causal link) will also be small.
“In summary, evidence for a causal association is not strong, these findings should be treated with caution, and pregnant women should be reassured.”
Prof Jean Golding, Emeritus Professor of Paediatric and Perinatal Epidemiology, University of Bristol, said: