Statistical analyses
Subject sociodemographic and clinical characteristics, and abdominal
muscle thicknesses, were recorded using descriptive statistics (mean±SD,
number, or percentage as required). Since some variables (onset of
labour, type of birth, sex of the baby) have been shown weakly related
to the study variables21,22, their role as potential
confounders was assessed. Finally, the associations shown by the
thickness of the abdominal muscles and the IRD, with birth-related
maternal and neonatal outcomes, were determined using partial Pearson
correlations after adjusting for maternal age, parity, BMI at the
16th w.g., and gestational age at birth. Values for
the duration of the first and second stages of labour, the Apgar test
score, and CB gas variables were adjusted for epidural analgesia. Given
that our group has previously described an association between maternal
flexibility in the third trimester of pregnancy and CB gas values at
birth23, the latter variables were adjusted for
flexibility at the 34th w.g. Analysis of covariance
(ANCOVA) was used to explore the differences in the duration of the
first and second stages of labour, and in neonatal CB gas values,
between women above or below the median IRD. Adjustments were also made
for being in the control or exercise group within the broader GESTAFIT
project14. All statistical analyses were performed
using SPSS Software for Windows, v.20.0 (IBM, Armonk, NY, USA).
Significance was set at p≤0.05.