Size at birth
The average stretched penile length at birth is about 4 cm (1.6 in), and 90% of newborn boys will be between 2.4 and 5.5 cm (0.94 and 2.17 in). Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm (2.4 in) with adult size reached about 5 years later. W.A. Schonfeld published a penis growth curve in 1943. Size with ageing
Authors of a paper reviewing research on area of penis sizes conclude that "flaccid penile length is just under 4 cm (1.6 in) at birth and changes very little until puberty, when there is marked growth. "Age is not believed to negatively correlate with penis size. "Individual research studies have... suggested that penis size is smaller in studies focusing on older men, but Wylie and Eardley found no overall differences when they collated the results of various studies [over a 60 year period]." Size and height
A 2015 review of the literature found two studies finding height and stretched or flaccid length to be moderately correlated, seven studies finding weak correlation for flaccid, stretched, or erect length, and two studies that found no correlation between flaccid length and height. Size and hands
One study investigated the relationship with digit ratio and found that men with longer ring fingers than index fingers had slightly longer penises. However, the common misconception that hand size predicts penis size has been widely discredited.
Both PCBs and the plasticizer DEHP have been associated with smaller penis size. DEHP metabolites measured from the urine of pregnant women have been significantly associated with the decreased penis width, shorter anogenital distance and the incomplete descent of testicles of their newborn sons, replicating effects identified in animals. According to a 2008 study published by the US National Library of Medicine, approximately 25% of US women have phthalate levels similar to those observed in animals.A 2007 study by the University of Ankara, Faculty of Medicine found that penile size may decrease as a result of some hormonal therapy combined with external beam radiation therapy. In addition, some estrogen-based fertility drugs like diethylstilbestrol (DES) have been linked to genital abnormalities or a smaller than normal penis (microphallus).A 2016 Korean study found that newborn male circumcision is associated with shorter penile length. Historical perceptions
Prehistory
Perceptions of penis size are culture-specific. Some prehistoric sculptures and petroglyphs depict male figures with exaggerated erect penises. Ancient Egyptian cultural and artistic conventions generally prevented large penises from being shown in art, as they were considered obscene, but the scruffy, balding male figures in the Turin Erotic Papyrus are shown with exaggeratedly large genitals. The Egyptian god Geb is sometimes shown with a massive erect penis and the god Min is almost always shown with an erection. Ancient
The ancient Greeks believed that small penises were ideal.