Strengths and Limitations
One of the strengths of this study is its focus on the effects of
extremely long IPIs, which is in accordance with the current birth
policy in China. Our results suggest that shorter and longer IPIs should
be a risk factor in subsequent pregnancy for women with a history of CS.
In addition, our analysis of the adverse pregnancy outcomes related to
IPI is relatively systemic, comprising scar-related morbidities and
common pregnancy morbidities.
The main limitation of our study is its retrospective design, which
precludes a power analysis. Moreover, the rate of trial of labor after
cesarean (TOLAC) was only 2.87% (n = 47), and the incidence of
uterine rupture may be underestimated. We could not accurately analyze
the effects of IPI on the success of VBAC or the risk of uterine rupture
for the small proportion of women with TOLAC. A larger, prospective
study would have to be carried out to identify candidates for TOLAC and
provide intensive prenatal care to guarantee safety during TOLAC. Our
previous systematic evaluation found that an IPI of more than 6-8 months
after CS can reduce the risk of adverse maternal and neonatal outcomes,
which is quite different from the results of this study. Our conclusions
regarding a short IPI are based on a small sample size and should thus
be interpreted with caution. Given that the WHO recommends an IPI of ≥24
months, further studies of a short IPI would have to be in a prospective
design.