Clinical characteristics and factors associated with short PR interval during late pregnancy: An age-frequency-matched retrospective study

BACKGROUND Short PR interval (<120 ms) is a recognized electrocardiographic finding during pregnancy, yet factors associated with its occurrence remain poorly understood. This study aimed to characterize women with short PR interval and identify clinical factors associated with its presence during late pregnancy. METHODS This age-frequency-matched retrospective study included 147 women with short PR interval and 197 with normal PR interval undergoing routine electrocardiography during late pregnancy (≥28 weeks). Correlation and multivariable logistic regression analyses were performed. Sensitivity analyses using predefined age strata and sequential exclusion of each age stratum assessed robustness to the age-matching structure. RESULTS Women with short PR interval had lower body mass index (BMI) (24.86 vs. 25.72 kg/m2, P = 0.006) and more advanced gestational age (39.4 vs. 39.0 weeks, P = 0.035). BMI was positively correlated with PR interval duration and remained significant after adjustment for potential confounders (partial r = 0.163, P = 0.003). In multivariable analysis, lower BMI (OR = 0.885, 95% CI 0.816-0.959, P = 0.003) and more advanced gestational age (OR = 1.167, 95% CI 1.003-1.358, P = 0.046) were independently associated with short PR interval. Sensitivity analyses showed generally consistent effect directions under alternative age adjustment and after sequential exclusion of age strata, although statistical significance varied in some reduced samples. CONCLUSIONS Lower maternal BMI and more advanced gestational age were associated with short PR interval during late pregnancy. However, the clinical significance of these modest associations remains uncertain and requires further investigation.