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Mode of delivery at periviable gestational ages: impact on subsequent reproductive outcomes

The optimum mode of delivery for infants in the periviable gestational period (23 – 26 weeks of gestation) has been an unanswered question. While authors have approached this question from many angles including comparing infant death rates by mode of delivery [1] to looking at different predictors for cesarean delivery, [2] no clear preference has been identified. To date, no prospective randomized controlled trials (RCT) have, or likely will be, performed for many reasons including rarity of cases, and large numbers of patients required to determine adequate power for an RCT. What is clearer is the use of cesarean delivery for abnormal presentation, primarily breech, in both term and preterm gestations. Hanna et al., in their landmark RCT trial comparing planned cesarean vs. planned vaginal delivery, found better outcomes with planned delivery even when taking into account maternal morbidity [3, 6] . Robilio et al., utilizing the California hospital discharge/ birth certificate database found a 10-fold increase in neonatal deaths in neonates with birth weights between 500 and 1000 g when delivered vaginally as compared to cesarean [4] . This latter study included gestational age ranges which most likely included the periviable period (23 weeks to 28 weeks) and would suggest that cesarean delivery for breech presentation may be beneficial at this time if viability is anticipated. For cephalic presentation, the data is less clear. Rothberger-Lannon et al., utilize the well-known Washington State Birth record database to try and answer another question concerning route of delivery in the periviable period, that of future pregnancy outcomes [5] . This question is an important one because delivering clinicians may be performing an operative delivery without clear proof of benefit to the current fetus and unknowingly setting up mothers for future bad outcomes. Their study is retrospective, from an administrative database, covers a long period of time (1989 – 2008), and thus includes all the limitations well known with these types of databases. The major outcomes of their study, however, are well documented in the Washington database and thus their data can be accepted at face value [5] . Their study design included separating women with periviable deliveries (20 – 26 weeks) into those with a cesarean or vaginal delivery. They then examined subsequent deliveries in these women for mode of delivery and maternal and neonatal morbidity and mortality. One issue with their study design was why did they include deliveries between 20 and 23 weeks if these were truly previable and not periviable ? An initial benefit to neonatal survival in cases with a prior cesarean section, was taken away when the < 23 week deliveries were removed [5] . There are several important take away points. The first is the significantly increased risk of uterine rupture (1.8% vs. 0.1%) in the subsequent pregnancy which uniformly had poor outcomes. Half of the eight cases were prior classical while the other half were reported as low transverse. Worse outcomes are expected in prior classical cesareans but this study suggests that all prior periviable cesareans should be treated the same. The authors also noted that the prior cesarean delivery group was delivered at an earlier gestational age and had a lower birth weight in the subsequent delivery. The authors felt this was most likely due to being delivered earlier due to the prior cesarean. In the end their data was mostly reassuring for future pregnancies in both groups with the above reservations. This data may help clinicians educate their patients about mode of delivery until more clear periviable delivery data becomes available.