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Table 2 Subgroup analyses of the impact of Caesarean section on subsequent sub-fertility (time to next pregnancy or birth)

From: Caesarean delivery and subsequent pregnancy interval: a systematic review and meta-analysis

Study characteristic Number of studies included Pooled OR estimate (95% CI) I2%
Overall pooled estimate n = 5 0.90 [0.86, 0.93] 30%
Parity    
Primiparous women only n = 2 0.91 [0.87, 0.96] 0%
Not limited to primiparous women n = 3 0.81 [0.73, 0.90] 0%
By publication date    
Pre-2000 n = 1 0.80 [0.68, 0.94] NA
Post-2000 n = 4 0.90 [0.86, 0.94] 19%
Length of follow-up    
<10 years n = 3 0.81 [0.73, 0.90] 0%
>10 years n = 2 0.91 [0.87, 0.96] 0%
Indication for mode of delivery    
Specified* n = 2 0.92 [0.88, 0.97] 88%
Not specified n = 3 0.81 [0.73, 0.90] 0%
By cohort size    
<35,000 n = 2 0.79 [0.67, 0.92] 0%
>35,000 n = 3 0.90 [0.87, 0.95] 13%
By definition of sub-fertility used    
a. Birth Interval (BI) n = 2 0.89 [0.84, 0.94] 44%
Inter-pregnancy interval (IPI) n = 3 0.91 [0.85, 0.97] 45%
b. Categorical measure (e.g. > 3 years) n = 3 0.81 [0.73, 0.90] 0%
Continuous measure (e.g. median IPI) n = 2 0.91 [0.87, 0.96] 0%
  1. Table Legend: Data refer to the pooled odds ratio (OR) and 95% confidence interval (CI) for each subgroup analysis. I 2 is a statistical measure of heterogeneity between 0% and 100%, with higher percentages implying great heterogeneity. *Specified: refers to the indication for mode of delivery and includes in Smith (2006) [18] assisted (instrumental) vaginal delivery, vaginal breech, elective Caesarean for breech, emergency Caesarean and all other prelabour Caesareans. For Tollanes (2007) [16] includes: breech presentation, low risk obstetric group, and a pre-eclampsia group.