Table 2.
Subgroup analyses of the impact of Caesarean section on subsequent sub-fertility (time to next pregnancy or birth)
| 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% |
Table Legend: Data refer to the pooled odds ratio (OR) and 95% confidence interval (CI) for each subgroup analysis. I2 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.