Effect of Maternal Cortisol Levels on Fetal Heart Rate Patterns

Objective: This study was designed to determine whether maternal cortisol levels affect fetal heart rate (FHR) patterns at third trimester. Design: Cross-sectional descriptive study. Setting: Prenatal wards of 1 public maternity services in Istanbul, Turkey. Participants: This study included 400 nulliparous pregnant women with uncomplicated pregnancies with a single fetus, between October 2022 and December 2022. Measurements and Findings: The minimum sample size required in the study was decided by power analysis. Effect size in the calculation: 0.35, type 1 error rate (α)=0.05, power of the study (1- β) 0.95 (Type II error=0.05) taken as. Accordingly, the minimum number of samples to be reached was calculated as 356 in total, and it was aimed to reach 392 samples, taking into account the 10% risk of loss. Research data will collect with the Data Collection Form. Noise level will measure with the Personal Noise Dosimeter. The FHR data will collect using a cardiotocograph. Saliva cortisol will measure by a microplate reader with commercially available kit based on ELISA.