ABSTRACT
BACKGROUND: It is thought that digit ratios (2D:4D) are a correlate of 1st trimester maternal and foetal sex steroids. Here we consider the relationship of 2D:4D to the former. METHOD: Digit lengths were directly measured with a calliper at infant age 13 months. Measures of T and E were obtained from mother's blood at 6-8 weeks, 10-11 weeks and 1st trimester means were calculated. RESULTS: There were 69 mother-infant pairs (33 boys). Sex differences in 2D:4D (boys