In this study, plan to undergo an elective CS at 36 weeks of gestation did not increase the risk of hemorrhage associated with CS for placenta previa on the side of the mother. Furthermore, risk such as tachypnea associated with preterm labor increased on the side of the neonate.
With intraoperative hemorrhage being the risk factor during CS for placenta previa, several factors such as complete placenta previa, anterior placentation, and placenta adhesion were reported [21–23]. Moreover, previous reports have indicated that the incidence of massive hemorrhage at CS for placenta previa increased as the gestational ages advanced [12, 13]. In our study, fewer cases with major placenta previa were included in the group scheduled to undergo an elective CS at 37 weeks of gestation. As a result, there were no significant differences in intraoperative hemorrhage at delivery between women who were scheduled to undergo an elective CS for placenta previa at 36 weeks of gestation and 37 weeks of gestation. Therefore, we performed univariate and multivariate analysis for intraoperative hemorrhage to confirm whether schedule at 37 weeks of gestation was the risk factor of intraoperative hemorrhage. Consequently, only intrauterine balloon tamponade was associated with intraoperative hemorrhage. Our previous reports demonstrated that rapid routine insertion of Bakri balloon could effectively reduce hemorrhage at delivery [19]. Thus, the use of Bakri balloon could delay the scheduled day CS for placenta previa without increasing intraoperative massive hemorrhage.
In pregnant women with placenta previa who underwent emergency CS, abrupt and massive hemorrhage occurred [24]. Because massive hemorrhage could result to serious complications, emergency CS should be avoided as much as possible for women with placenta previa. Hence, this is the same for the neonates. This setting could result to neonatal anemia, prematurity, and mortality [11,25,26]. In our study, there were no statistical significances of rate of emergency CS for both groups. Therefore, CS scheduled at 37 weeks of gestation was permissible.
According to the previous reports of the neonatal outcome following elective CS with low risk, even though the timing of delivery is at term, the incidence of adverse events including respiratory and other adverse neonatal outcomes gradually increased until 39 weeks of gestation [27]. Our study demonstrated that CS scheduled at 36 weeks of gestation increased neonatal adverse events such as respiratory disorder and neonatal hypoglycemia. Thus, CS scheduled at 37 weeks of gestation might be recommended on the side of the neonate. With these results, we assumed CS scheduled after 38 weeks of gestation for placenta previa might decrease neonatal adverse events such as respiratory disorder and neonatal hypoglycemia. However, it was a challenging problem. It was unclear whether CS scheduled after 38 weeks of gestation because of placenta previa did not increase the risk including massive hemorrhage or emergency CS on the side of the mother. Further study should examine this problem.
This study had several limitations such as the fact that this is retrospective study that was conducted in a single institution with a small sample size. Furthermore, there was a selection bias that patients with high risk of massive hemorrhage were likely to be scheduled to undergo an elective CS at 36 weeks of gestation based on the judgment of the doctors. However, Blackwell SC et al. pointed out that there were available data to resolve the problem [18]. Therefore, we believed our results were useful for further studies.
In conclusion, there was no difference in maternal outcome between women who were scheduled to undergo an elective CS at 36 weeks or 37 weeks of gestation for placenta previa regardless of selection bias. On the other hand, neonatal complications increased in neonates of women who were scheduled to undergo an elective CS at 36 weeks of gestation. Based on this result, further studies are required to evaluate when elective CS for placental previa should be scheduled.