The first study, of 3,000,000 Canadian deliveries found an association
between medical induction of labour and AFE (odds ratio of
1.8).29 The authors suggested that women contemplating elective
induction should be informed of this risk (an absolute risk of 1 in
10,000). Remarkably, a very similar study of 3,000,000 US deliveries
using the same methodology (and even sharing one author) found no
statistically significant association between labour induction and AFE
although some of the other associations (Caesarean delivery) remained
robust.28 The most important point of these studies is that even an
analysis of several million deliveries at a time might not produce consistent
associations, let alone permit cause and effect deductions. The
disease is rare, there are numerous confounding variables, and
although there may be a consensus about diagnostic criteria in the
medical literature, it is easy to surmise that this knowledge is not uniform
among practicing obstetricians.