Statistical analyses
Descriptive statistics was compiled, tabulated and presented as absolute
numbers with means or medians and corresponding standard deviation or
interquartile range, depending on covariate distribution. To assess the
impact of clinical and laboratory characteristics of deliveries
complicated by chorioamnionitis the cohort was - for this specific
question - treated as a case-control study, where the specific
characteristics of chorioamnionitis was the exposure and composite
adverse neonatal outcome was the outcome. Logistic regression models
were used to estimate odds ratios (ORs) of the association between each
exposure and risk of neonatal outcomes. Inflammatory laboratory
measurements were categorized into tertiles, with the lowest tertile
used as a reference. A multivariate model adjusted for maternal age at
delivery, smoking status, BMI and parity. All analyses were performed
using SASĀ® Software (Statistical Analysis Software version 9.4, SAS
Institute Inc, Cary, North Carolina, USA).