Prenatal smoke exposure is associated with increased anogenital distance in female infants: a prospective case-control study

Abstract

Objectives: To investigate the effects of maternal smoking during pregnancy on newborn infants' anogenital distance (AGD).

Methods: Fifty-six female and sixty-four male newborn infants from mothers who smoked during pregnancy were included in this study. A control group for each sex was selected from infants whose mothers had no active or passive (in either the household or the workplace) smoke exposure before or during pregnancy. Questionnaire data on maternal demographic characteristics and information about cigarette use were collected. We assessed genital anthropometry which included AGD for both male and female neonates, and stretched penile length (SPL), penile girth for males within the first 48 h after birth. AGD measurements were also normalized according to birth weight (AGD/weight in grams), length (AGD/height in millimeters), and ponderal index [AGD/(weight in grams/height in cubic centimeters)]. Anogenital index (AGI) was calculated by dividing the AGD by cube root of birth weight.

Results: In female infants, prenatal smoke exposure was associated with significantly increased weight-adjusted AGD (p=0.03). There was also a significant correlation between mothers' daily smoking rates and weight-adjusted AGD (r=0.27/p=0.03). In male infants, fetal smoke exposure was not associated with any AGD measurements, SPL and penile girth.

Conclusions: A significant increase in weight-adjusted AGD in female infants exposed to maternal smoking may be an indicator of antenatal androgen exposure and may pose a risk for short and long-term endocrine, metabolic and behavioral problems.

Keywords: androgenic effect; anogenital distance; fetal smoke exposure.