title: Human anogenital distance: an update on fetal smoke-exposure and integration of the perinatal literature on sex differences.
abstract: OBJECTIVE
  Do sex and maternal smoking effects on human fetal anogenital distance (AGD) persist in a larger study and how do these data integrate with the wider literature on perinatal human AGD, especially with respect to sex differences?
  
  
  CONCLUSIONS
  Second trimester sex differences in AGD are broadly consistent with neonatal and infant measures of AGD and maternal cigarette smoking is associated with a temporary increase in male AGD in the absence of changes in circulating testosterone.
  
  
  BACKGROUND
  AGD is a biomarker of fetal androgen exposure, a reduced AGD in males being associated with cryptorchidism, hypospadias and reduced penile length. Normative fetal AGD data remain partial and windows of sensitivity of human fetal AGD to disruption are not known.
  
  
  METHODS
  The effects of fetal sex and maternal cigarette smoking on the second trimester (11-21 weeks of gestation) human fetal AGD were studied, along with measurement of testosterone and testicular transcripts associated with apoptosis and proliferation.
  
  
  METHODS
  AGD, measured from the centre of the anus to the posterior/caudal root of penis/clitoris (AGD(app)) was determined in 56 female and 70 male morphologically normal fetuses. These data were integrated with current literature on perinatal AGD in humans.
  
  
  RESULTS
  At 11-13 weeks of gestation male fetal AGD(app) was 61% (P< 0.001) longer than in females, increasing to 70% at 17-21 weeks. This sexual dimorphism was independent of growth characteristics (fetal weight, length, gonad weight). We confirmed that at 14-16 weeks of gestation male fetal AGD(app) was increased 28% (P < 0.05) by in utero cigarette smoke exposure. Testosterone levels were not affected by smoking. To develop normative data, our findings have been integrated with available data from in vivo ultrasound scans and neonatal studies. Inter-study variations in male/female AGD differences lead to the conclusion that normalization and standardization approaches should be developed to enable confidence in comparing data from different perinatal AGD studies.
  
  
  CONCLUSIONS
  Sex differences, and a smoking-dependent increase in male fetal AGD at 14-16 weeks, identified in a preliminary study, were confirmed with a larger number of fetuses. However, human fetal AGD should, be re-assessed once much larger numbers of fetuses have been studied and this should be integrated with more detailed analysis of maternal lifestyle. Direct study of human fetal genital tissues is required for further mechanistic insights.
  
  
  CONCLUSIONS
  Fetal exposure to cigarette smoke chemicals is known to lead to reduced fertility in men and women. Integration of our data into the perinatal human AGD literature shows that more work needs to be done to enable reliable inter-study comparisons.
  
  
  BACKGROUND
  The study was supported by grants from the Chief Scientist Office (Scottish Executive, CZG/1/109 & CZG/4/742), NHS Grampian Endowments (08/02), the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 212885 and the Medical Research Council, UK (MR/L010011/1). The authors declare they have no competing interests, be it financial, personal or professional.
authors.affiliation: Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK p.a.fowler@abdn.ac.uk.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Fowler
authors.affiliation: Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Filis
authors.affiliation: Institute of Applied Health Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: Siladitya
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: USC INRA 1329 Laboratoire d'Etude des Résidus et Contaminants dans les Aliments, LUNAM Université, Oniris, Nantes F-44307, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: le Bizec
authors.affiliation: USC INRA 1329 Laboratoire d'Etude des Résidus et Contaminants dans les Aliments, LUNAM Université, Oniris, Nantes F-44307, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Antignac
authors.affiliation: USC INRA 1329 Laboratoire d'Etude des Résidus et Contaminants dans les Aliments, LUNAM Université, Oniris, Nantes F-44307, France.
authors.forename: Marie-Line
authors.initials: ML
authors.lastname: Morvan
authors.affiliation: Endocrinology Unit, Queen's Medical Research Institute, University/BHF Centre for Cardiovascular Science, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Drake
authors.affiliation: Institute of Biodiversity, Animal Health & Comparative Medicine (IBAHCM), College of Medical, Veterinary & Life Sciences, University of Glasgow, Bearsden Rd, Glasgow G61 1QH, UK.
authors.forename: Ugo
authors.initials: U
authors.lastname: Soffientini
authors.affiliation: Institute of Biodiversity, Animal Health & Comparative Medicine (IBAHCM), College of Medical, Veterinary & Life Sciences, University of Glasgow, Bearsden Rd, Glasgow G61 1QH, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: O'Shaughnessy
mesh_terms: D000328:Adult; D001003:Anal Canal / Q000033:anatomy & histology; D001837:Body Weights and Measures; D002987:Clitoris / Q000033:anatomy & histology; D003367:Cotinine / Q000097:blood; D005260:Female; D047109:Fetal Development / Q000187:drug effects*; D006801:Humans; D007223:Infant; D008297:Male; D008423:Maternal Age; D010413:Penis / Q000033:anatomy & histology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011297:Prenatal Exposure Delayed Effects; D012727:Sex Characteristics; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects*; D013739:Testosterone
chemical_list: D012906:Smoke; D013739:Testosterone; D003367:Cotinine
keywords: anogenital distance; apoptosis; dysregulation; endocrine-disrupting chemicals; fetus; maternal cigarette smoking human; normative data; proliferation; second trimester; testosterone