I read with great interest the recent article by Tucker Edmonds et al. I would like to congratulate the authors on an important contribution to the literature. Their claim that they have provided a more nuanced understanding of factors that may explain previous reports that cesarean delivery confers a survival advantage for periviable neonates is correct and important to emphasize. This is an important extension of the previous literature.

I disagree only with the phrasing of some of the conclusions, namely, “Cesarean delivery increased overall survival and major morbidity for breech periviable neonates” and “Our findings demonstrate a survival advantage with cesarean delivery among the entire cohort of intubated and non-intubated 23- and 24- week breech neonates.” Arguably, many readers may see only these conclusions, which do not represent correctly what this important article demonstrates. Even though the authors performed an appropriate evaluation of numerous confounding factors using regression analysis, which showed the factors that have an independent association with the outcome in question, because this is an observational and retrospective evaluation of vaginal versus cesarean delivery, the correct way to describe the findings is with the phrase “there was an association of improved survival with cesarean delivery.” It is extremely important to avoid conveying that cesarean delivery produced this advantage. Observational studies cannot evaluate causation, only associations.

I realize it is devilishly difficult to avoid reverting to a description such as the authors used because it must appear in several locations and the temptation is to use a different phrase in order not to appear redundant. Nevertheless, it is critical to be careful in describing the results.

I also believe it imperative to emphasize another finding that the authors report (although I would phrase it differently using the phrase “was not associated with.”). “Finally, cesarean delivery did not confer a survival benefit to neonates who weighed <500 grams.” The most extremely premature or periviable infants are not likely to benefit. The explosion in cesarean deliveries in the past several decades may not be justified for many reasons, particularly for these most premature fetuses. The danger in the use of language that implies causation is that obstetricians may extend the presumed benefits to all fetuses, which would produce major morbidity and mortality rates from cesarean deliveries that would be performed without indication, without any benefit to the newborn infants.

We must remember that association does not mean causation.