Maternal β-hCG and neonatal hormone profiles as predictors of anogenital distance: assessing the fetal reproductive axis.

OBJECTIVES

To evaluate the association of maternal β-human chorionic gonadotropin (β-hCG), neonatal thyroid hormones including free triiodothyronine (fT3), free thyroxine (fT4), and thyroid-stimulating hormone (TSH), and neonatal serum testosterone with anogenital distance (AGD) in term male and female newborns, and to assess sex-related differences.

METHODS

This hospital-based cross-sectional study included 133 term newborns (90 males and 43 females) delivered between 37 and 40 weeks of gestation. Maternal serum β-hCG levels were measured before delivery. Cord blood samples were analyzed for fT3, fT4, TSH, and neonatal venous blood samples for serum testosterone. AGD and neonatal anthropometric parameters were measured shortly after birth. Sex-wise comparisons and correlation analyses were performed.

RESULTS

Mean AGD was significantly greater in male newborns than in females (2.62 ± 0.09 cm vs. 1.15 ± 0.05 cm; p = 0.001). Maternal β-hCG levels differed between mothers of male and female newborns (p<0.05). Neonatal serum testosterone levels were higher in males, though not statistically significant (p=0.16). AGD showed positive correlations with maternal β-hCG and neonatal serum testosterone levels. Among thyroid hormones, mean fT3 levels were significantly higher in females (p=0.0001), while fT4 and TSH were comparable.

CONCLUSIONS

AGD at birth shows marked sexual dimorphism and is associated with maternal β-hCG and neonatal serum testosterone measured at birth. These findings provide reference data from an Indian newborn population. Given the timing of measurements, results should be interpreted with caution, and further longitudinal studies are required to clarify developmental determinants of AGD.