The different roles of androgens in the human male during the presumptive fetal masculinization programming window (MPW; organizational/programing effects) and during postnatal life (mini-puberty and puberty; growth and activational effects), in relation to average blood testosterone levels (solid black line).

Anogenital distance (AGD; fetal life) or anoscrotal distance (ASD; postnatal life) is shown to illustrate how androgen exposure in the MPW programs longer AGD/ASD in males than in females, a change evident already in mid-pregnancy; in females the equivalent measurement to ASD is from the center of the anus to the fourchette (AFD). Note that the absolute length of ASD increases postnatally under the influence of postnatal androgens, primarily during mini-puberty. ASD rather than AGD is shown for postnatal males as this is the measurement most commonly used in epidemiological studies, but comparable sex differences are evident in postnatal AGD as for ASD, except AGD is much longer than ASD (e.g. in adult males AGD = 121–140 mm versus 44–60 mm for ASD). Direct measurement of AGD is only available between 11 and 18 weeks’ pregnancy but measurement by ultrasound is available later in pregnancy (see text) but is not illustrated. Note that for adult males, mean values for ASD are illustrated from four independent studies to give an idea of the variation in adult male ASD. The illustration is based on data from the literature [11–14,30–33,37] with childhood data based on mean reference data obtained using the Cambridge measurement method [12].