Investigation of the relationship between the morphological and personal characteristics of mothers and newborn infants and their 2D:4D ratios

The second-to-fourth digit ratio (2D:4D) has been used as an indirect method to investigate the potential effects of exposure to prenatal (intrauterine) hormones. It has been noted that this rate is lower in men than in women. The digit ratio has been associated with the prenatal balance of estrogen and androgen, which is thought to underlie this sex difference. Therefore, the relationship between hormonal levels in the womb and neonatal morphometry is considered important for future generations. The aim of this study was to examine the relationship between the 2D:4D digit ratio in mothers and newborns and morphological characteristics, personal characteristics, personality traits, and nutritional attitudes. In addition, the relationship between the 2D:4D ratio and anthropometric measurements and handgrip strength was also evaluated. The study was conducted at the Postpartum and Cesarean Units of Malatya Training and Research Hospital between 01.09.2025 and 01.01.2026. A total of 160 individuals, including 80 mothers and 80 newborns, were included in the study. Sociodemographic data of mothers, personality traits (Big Five Personality Inventory), and nutritional attitudes (Nutritional Attitude Scale) were assessed. Height and weight measurements of mothers and newborns were taken using a stadiometer and scale, and head circumference measurements were taken using a measuring tape. Index and ring finger lengths were measured using a digital caliper, and 2D:4D ratios were calculated from these measurements. Handgrip strength in mothers was assessed using a digital dynamometer. Statistical analysis of the data was performed using SPSS software. A statistically significant relationship was found between family history of psychiatric disorders in the mother (p = 0.026) and maternal psychiatric history (p = 0.006) with left-hand 2D:4D. A statistically significant relationship was found between the 2D:4D ratio of the newborn's right hand and blood group distribution (p = 0.009). In addition, a statistically significant relationship was found between the father's educational level and the newborn's left-hand 2D:4D ratio (p = 0.028). In conclusion, these findings can contribute to the literature by revealing the relationship between the 2D:4D ratio in mothers and newborns and biological and behavioral characteristics. KEYWORDS: 2D:4D ratio, mother and newborn, anthropometry, nutritional attitude, personality traits