Dear Editor,

A case may be made that increased maternal testosterone is involved in increased preterm births. Black, pregnant women produce more testosterone than white women (Cancer Epidemiol Biomarkers Prev 2005; 14: 1514-20) and black births exhibit increased premature births.

Learning disabilities in children have been connected with increased testosterone (Physiol Behav 1993; 53: 583-6). Populations of individuals with increased levels of testosterone may tend to congregate in lower "socioeconomic" areas as a result of lack of employment because of increased need for advanced education in societies increasingly reliant on increased education. This would also apply to any ethnic group but may be increased in the black population.

I suggest the findings of Smith, et al., may be explained by increased testosterone levels within lower socioeconomic circumstances.