We thank Drs Cobo, Kacerovsky, and Jacobsson for their insightful comments. When the associations between infection, inflammation, and neonatal morbidity are being analyzed, it is critical to adjust for the independent contribution of gestational age. But which gestational age? In patients with preterm labor, early gestational age at presentation is associated with high prevalence of intraamniotic infection and inflammation, whereas early gestational age at delivery is associated with high rates of neonatal complications.

It is not obvious a priori whether it is better to adjust for gestational age at presentation or gestational age at delivery, so we performed logistic regressions using both types of adjustment (our Table 6). We cannot recall any previous papers in which this was done. We were surprised to find that adjustment for gestational age at delivery seemed to negate the finding that intraamniotic infection and inflammation were associated with increased perinatal morbidity. Indeed, as Cobo et al point out, we found that severe intraamniotic inflammation was associated with decreased neonatal morbidity, primarily respiratory distress, after performing this adjustment. We are intrigued by their suggestion that intraamniotic inflammation may accelerate fetal lung maturation.

We will be interested to see whether other groups replicate these findings. Meanwhile, we do not wish to imply that intraamniotic infection and inflammation are benign conditions in women with preterm labor. Infection and inflammation are most prevalent at <32 weeks of gestation and are associated with very short latency to delivery, so they are associated with very high rates of perinatal morbidity and mortality (our Table 5). Based on the logistic regressions (models 3 and 4 in our Table 6), we suggest only that infection and inflammation may cause these complications indirectly, that is, by triggering early preterm birth and not by direct injury to the fetus/newborn infant.