Digit ratio links prenatal hormone exposure with adult lung function

0.94 ± 0.30 to female values of 0.961 ± 0.033.2 A separate study of adult male Han reported similar digit ratio values of 0.9478 ± 0.0322 for the right hand.3 Park and coworkers1 postulated that age may have had an effect on digit ratio, but if so, the effect must have been subtle since age was not significantly correlated with digit ratio in males or females in their study. Furthermore, the utility of using digit ratio as a biomarker resides in its relative stability throughout life; admittedly, more attention has been paid to postnatal and pubertal modulations of digit ratio.4 Thus, investigation of age-related hormonal events later in life (e.g. menopause) and their influence on digit ratio may be warranted. So then, does it matter that typical sex differences in digit ratio were not upheld in the present study? The researchers have claimed that low digit ratio is predictive of poor lung function in adulthood. The proposed explanation is a higher prenatal exposure of testosterone leading to compromised airway development. A possible flaw in this argument is that females in the study had the lowest digit ratios, yet they had better-than-predicted lung function and fewer females than males demonstrated compromised airflow, which is contrary to predictions of the study. Despite some shortcomings in generalizability, due largely to the anomalous digit ratios of female participants, the overall association of digit ratio with several parameters of lung function is convincing. Perhaps the study could be replicated using participants of a different age range and/or ethnicity to further test the predictive value of digit ratio on airway function. Given the prevalence of airway diseases like chronic obstructive pulmonary disease and increasing discoveries of endocrine disruptors in the environment, attention should be paid to this study that links prenatal steroid exposure with adult lung function.