The effect of first trimester body mass index on the changes in the upper lip bite test classification before and after delivery: A prospective observational study.

Background: The difficult airway (DA) assessment and management of pregnant woman has always brought specific challenges. The aim of this study was to investigate the effect of labor on the airway by assessing changes in the upper lip bite test (ULBT) classes and to explore its correlation with the first trimester's body mass index (BMI).

Methods: According to the BMI of the first trimester, 354 full-term women were divided into low BMI group, normal BMI group and high BMI group.