Strengths and Limitations
Strengths of this study include use of a large diverse cohort, allowing
for subgroup analysis and larger generalization of the results.
Assessment of resting intrauterine tone is novel and addresses a
quandary that is identified in clinical practice. There are several
limitations to this study. First, placement of IUPC at our institution
is not universal and thus the cohort is subject to selection bias.
Additionally, our database only included the last 120 minutes of IUPC
data, limiting our analysis to this timepoint. Due to a paucity of data
on the average or “normal” resting intrauterine tone there is no
established definition of elevated tone. We chose ≥ 75%, however,
further investigations with larger sample sizes should be used to
determine a possible threshold resting tone that is associated with
uterine hypoperfusion and neonatal morbidity The majority of patients
delivered vaginally and were primarily in the second stage of labor for
the duration of available IUPC data. Thus, we were unable to assess the
effects of elevated resting tone throughout the first stage of labor.
Lastly, while the number of patients included in the study was sizable
it remains underpowered for individual analysis of rare adverse events
leading to the need for a composite outcome with the potential bias
associated with pooling outcomes.