Caesarean delivery without TOL
Caesarean delivery without TOL risks were higher for SGA
<5th percentile (25.2% versus 23.7%) and
SGA <3rd percentile (26.2% versus 23.7%;Table 1 ) compared to AGA. A more nuanced picture emerges when
this outcome is stratified by gestational age. For example, 77.5% of
women who delivered at <34 weeks with SGA
<5th percentile were delivered by caesarean
without TOL compared to 48.3% of AGA births whereas the risk was
substantially lower at 41 weeks and beyond (10.9% versus 8.0%).
Although risks of caesarean delivery without TOL decreased across
gestational age for SGA and AGA births, the caesarean risks without TOL
were higher for SGA <5th percentile at each
gestational age strata except for 39-40 weeks’ gestation (when 22.9% of
SGA <5th percentile births were Caesarean
without TOL compared to 24.5% of AGA births). These same trends, though
more pronounced, were observed for SGA <3rdpercentile births.
The results of the mediation analysis for caesarean delivery without TOL
and exposure to SGA <5th percentile are
described in Table 2 . For SGA versus AGA births, the adjusted
excess risk of caesarean delivery without trial of labour had a “U”
shaped association, with increased risk at preterm gestations, lowest
risk at 39-40 weeks, and increased risk at ≥41 weeks. The decomposition
analysis revealed that the driver of this excess risk was the CDE with
minimal mediation and interaction components. The mediation analysis for
this outcome and exposure to SGA <3rd percentile revealed
similar, but more pronounced, patterns (Table 3 ).