Multivariable logistic regression analysis of the associations
between other pregnancy outcomes and IPIs (Tables 4, 5, 6, 7, 8, and 9)
Multivariable logistic regression analysis using an IPI of 24-59 months
as the reference category was conducted to examine the associations
between different IPIs and adverse perinatal outcomes among 1662 women
with previous CS. Model 1 did not adjust for any confounding factors
(Table 4), while model 2 adjusted for maternal age, maternal BMI,
educational status, assisted reproductive technology (ART), number of
previous CSs, previous vaginal delivery and previous emergency CSs
(Table 5). In model 1, an IPI of less than 24 months significantly
increased the risk of incomplete uterine rupture (OR 1.30, 95% CI
1.05-1.61), while an IPI of 60 to 119 months (OR 0.77, 95% CI
0.62-0.95) and 120 months or greater (OR 0.59, 95% CI 0.38-1.08)
significantly reduced the risk of incomplete uterine rupture. In model
2, after adjustments for some confounders, the results suggested that
the IPI was not a risk factor for incomplete uterine rupture. In models
1 and 2, we found that IPI had no effect on other adverse perinatal
outcomes, including pernicious placenta, abnormal placental position,
PROM, PPH, hysterectomy, low 1-min Apgar score, and admission to the
NICU.
Studies have confirmed that emergency CS can significantly increase the
risk of adverse perinatal outcomes.22 The other four
models were established by using multivariable logistic regression
analysis to analyze the relationship between the IPI of 552 women with
emergency CS and that of 1099 women with elective CS and perinatal
outcomes separately. Model 3 did not adjust for any confounding factors
in women with emergency CS (Table 6), while model 4 adjusted for
maternal age, maternal BMI, educational status, ART, number of previous
CSs, and previous vaginal delivery (Table 7). In models 3 and 4, the
association between IPI and incomplete uterine rupture among women with
emergency CS always remained nonsignificant (p > 0.05).
Model 5 did not adjust for any confounding factors among women with
elective CS (Table 8), while model 6 adjusted for maternal age, maternal
BMI, educational status, ART, number of previous cesarean sections, and
previous vaginal delivery (Table 9). In model 5, IPI was a risk factor
for incomplete uterine rupture (p = 0.048). An IPI of less than 24
months significantly increased the risk of incomplete uterine rupture
(OR 1.35, 95% CI 1-1.82), and an IPI of 60 to 119 months (OR 0.74, 95%
CI 0.55-1) or 120 months or greater (OR 0.55, 95% CI 0.3-0.99)
significantly reduced the risk of incomplete uterine rupture. In model
6, after adjustments for some confounders, we found that the IPI of
women with a history of selected CS was not a risk factor for incomplete
uterine rupture (p = 0.131).