Part 2
The 25 delivery units participating in the study, accounted for 82.1%
of the deliveries in Norway (Tab. 1, Fig. 2).
The characteristic of the birth population from participating and
non-participating units revealed minor, but statistically significant
differences in maternal age, pre-pregnancy BMI, parity, start of labour,
gestational age at delivery, and transfer to the neonatal intensive care
unit (Tab. 1). The categorization of the entire birth population
according to the TGCS (which is standard practice in (Norway) is shown
in Tab. 2, and of those the groups 1, 2a, 3, 4a and 5 were included in
the study. Of eligible women, 8.7% had missing data due to missing
study forms (Fig. 2).
The CSs were classified according to the classification and within the
study group shown in Figure 4 (Supplement 3). In both nulliparous and
parous women (without a previous CS), induction of labour (Group 2a and
4a) compared to spontaneous onset of labour (Group 1 and 3) was
associated with a significant higher proportion classified as CS for
fetal indication (no oxytocin), dystocia-inefficient uterine
action-oxytocin-poor response and dystocia-inefficient uterine action-
oxytocin-inability to treat fetal intolerance (Fig. 4, Supplement 3). In
women with a previous CS, induction of labour (Group 5b) compared to
spontaneous start of labour (Group 5a) was associated with a higher
proportion of CS classified as dystocia-inefficient uterine
action-oxytocin-poor response and dystocia-inefficient uterine
action-inability to treat-fetal intolerance. The prevalence of CS
classified as dystocia-efficient uterine action (CPD or malposition) was
generally low in all groups. In dystocic labour in women with a previous
CS (Group 5) there was a greater prevalence of CS classified as
dystocia-inefficient uterine action-no oxytocin compared to the
remaining study population (Groups 1-4) (Fig. 4, Supplement 3).