With these caveats in mind, British investigators have probably the
best data and analytic methods with which to measure clinical associations
with AFE.5,31 They used a customized database, specifically
assessed potential AFE cases, and used control patients from women
delivering in the same hospital immediately before the index case. They
found an association with labour induction (adjusted odds ratio 3.86),
older, ethnic minority women (adjusted OR 9.85), and multiple pregnancy
(adjusted OR 10.9). Caesarean section was associated with postnatal
AFE (adjusted OR 8.84). A regression model was developed in an
effort to sort out confounding variables. Although a much more rigorous
treatment of clinical associations of AFE in a large population
than other studies, cause and effect relationships should still be treated
with caution. In particular, it is unclear why age should be associated
with AFE—but only for ethnic minorities and not Caucasians. (The
strength of this relationship was almost three times stronger than with
induction of labour.)