Investigating the ratio between the lengths of the second and fourth fingers in newborns: its relationship with the umbilical cord testosterone level at Shahidan-e-Mobini hospital during the year 2021

Abstract Objectives: The second finger to the ring finger or fourth finger (2D:4D ratio) has been used to predict androgen-related diseases in various studies. However, few studies have investigated this ratio at birth, therefore, the aim of the present study was to determine the relationship between the 2D:4D ratio and the umbilical cord testosterone level in the Shahidan-e-Mobini hospital, Sabzevar in 2021. Material & Methods: The present study is a cross-sectional and prospective study that was conducted on a convenience sample of 124 NICU newborns of Shahidan-e-Mobini hospital in Sabzevar in 2021. At the time of delivery, two cc of blood was taken from the mother's umbilical cord to determine its serum testosterone level. Also, the length of the second and fourth fingers was measured during the first few hours after birth, 2D:4D ratio was calculated and finally compared with the testosterone level, gestational age, and birth weight. Data analysis was carried out using SPSS version 21. P-value<0.05 was considered as the significance level. Results: The results of the present study showed no significant correlation between the testosterone blood level and 2D:4D ratio in both males and females (P>0.05). There was a significant negative and positive correlation between birth weight and 2D:4D ratio in boys and in girls, respectively, but the correlation coefficient was low in both cases. There was also a significant negative correlation between gestational age with the 2D:4D ratio in males. Conclusion: The results of the present study showed that the typical sexually dimorphic pattern was not seen in 2D:4D ratio. Also, no androgen-dependent pattern was seen in the 2D:4D ratio.