Determination of the normal range of anogenital distance in full-term neonates in Shanghai and analysis of influencing factors / 中华实用儿科临床杂志

ABSTRACT

Objective:To provide a normal reference range for anogenital distance (AGD) in full-term neonates and to investigate factors possibly affecting neonatal AGD.Methods:Neonates with gestational age ≥37 weeks who were delivered in the Ruijin Hospital Affiliated to Shanghai Jiaotong University School of Medicine from November 2017 to March 2019 were enrolled.General information on mothers and newborns were collected and neonatal AGD were measured.The distance from the male anus center to the base of the scrotum was determined to be the male AGD, and the distance from the female anus center to the posterior labia was recorded as the female AGD.The effects of maternal and neonatal factors on neonatal AGD were analyzed.Results:A total of 1 078 newborns were included, including 586 males and 492 females.Male AGD [(22.90±3.80) mm] was significantly greater than female AGD [(11.80±2.10) mm] ( t=22.316, P<0.05). The AGD of singleton neonates was significantly greater than that of neonatal twins [males (23.01±3.82) mm vs.(21.18±1.88) mm, females (11.89±2.08) mm vs.(10.98±1.75) mm, t=26.185, 18.326, all P<0.05]. Neonatal gestational age, birth weight, head circumference and length were significantly associated with AGD (all P<0.05). Maternal factors (including age, height, weight, body mass index, gravidity, parity, occupation, etc.) were not significantly associated with neonatal AGD (all P>0.05). The AGD of 10 children with genital malformation was significantly smaller than that of males with normal genital appearance [(22.89±1.99) mm vs.(23.55±3.78) mm]( t=15.362, P=0.006). Conclusions:The reference ranges of AGD in full-term males and females in Shanghai are(22.90±3.80) mm and (11.80±2.10) mm, respectively.The neonatal gestational age, birth weight, head circumference and length may be the intrinsic factors affecting neonatal AGD.