Association between the Ratio of the Length of the 2nd Digit and the 4th Digit of the Hand and Heart Rate Variability in Apparently Healthy Young Males

Abstract Background: The length of the 2 nd digit and the 4 th digit of the hand (2D:4D), a putative marker of prenatal androgen exposure, is associated with cardiovascular risk in males. Heart rate variability (HRV) is an established predictor of cardiovascular morbidity and mortality. While both parameters have independently been linked to cardiovascular health, their direct association has not been adequately explored in healthy populations. Objective: To evaluate the association of 2D:4D digit ratio with HRV and arterial blood pressure in apparently healthy young males. Methods: This cross-sectional study recruited 100 healthy males, aged 18–45 years. Digit lengths and short-term HRV were assessed using standardised methods. Arterial blood pressure was also recorded. Statistical analysis was performed using Spearman’s correlation, with P < 0.05 considered statistically significant. Results: The mean age of participants ( n = 92) was 31.9 ± 8.1 years. No statistically significant correlation was observed between 2D:4D (right or left hand) and HRV parameters ( P > 0.05). A weak statistically significant positive correlation was found between the digit ratio of right hand (R2D:4D) and systolic blood pressure (SBP) ( r = 0.25, P = 0.02). No significant associations were observed with diastolic BP. Conclusion: No significant association between 2D:4D and HRV was observed in healthy young males. However, the positive correlation between the R2D:4D and SBP suggests a possible influence of prenatal hormonal exposure on adult cardiovascular parameters.