The effect of mode of delivery and duration of labour on subsequent
pregnancy outcomes: a retrospective cohort study
Objective To assess if delivery mode and duration of labour in
a first labour of spontaneous onset is associated with gestational
length, delivery mode 3and neonatal outcome in the subsequent pregnancy.
Study Design Retrospective analysis of prospectively collected
data. Setting 15 Maternity units in North West London (1988 to
2000). Population 30,840 women with spontaneous onset of labour
in pregnancy 1 and a subsequent birth reported in the same database.
Methods Assessment of outcomes by mode of delivery in pregnancy
1, restricting the analysis to the difference in the gestational length
between pregnancy 1 and 2. Main Outcome Measures Gestational
length, mode of delivery and neonatal unit admission in pregnancy 2.
Results Caesarean section (CS) in the first or second stage of
labour in pregnancy 1 was associated with pregnancy 2 being a median of
5 and 8 days shorter and a preterm birth rate of 6.0% and 10.1%
respectively, whereas following a spontaneous or instrumental birth in
pregnancy 1 the median duration was similar, with preterm delivery rates
of 4.5% and 3.9%. 56.2% of women with a CS in pregnancy 1 had a
repeat CS and 12.5% of their babies were admitted to neonatal unit,
compared with 5.3% of women with vaginal birth. Longer labours were
associated with shorter gestations in pregnancy 2. Conclusions
Compared to vaginal birth, an emergency CS in the first term pregnancy
is associated with a shorter gestational length, increased rate of
repeat CS and increased risk of NNU admission in the next pregnancy.