title: The effect of fetal sex on customized fetal growth charts.
abstract: OBJECTIVE
  To evaluate the effect of fetal sex on singleton pregnancy growth charts customized for parental characteristics, race, and parity Methods: In a multicentric cross-sectional study, 8070 ultrasonographic examinations from low-risk singleton pregnancies between 16 and 40 weeks of gestation were considered. The fetal measurements obtained were biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL). Quantile regression was used to examine the impact of fetal sex across the biometric percentiles of the fetal measurements considered together with parents' height, weight, parity, and race.
  
  
  RESULTS
  Fetal gender resulted to be a significant covariate for BDP, HC, and AC with higher values for male fetuses (p ≤ 0.0009). Minimal differences were found among sexes for FL. Parity, maternal race, paternal height and maternal height, and weight resulted significantly related to the fetal biometric parameters considered independently from fetal gender.
  
  
  CONCLUSIONS
  In this study, we constructed customized biometric growth charts for fetal sex, parental, and obstetrical characteristics using quantile regression. The use of gender-specific charts offers the advantage to define individualized normal ranges of fetal biometric parameters at each specific centile. This approach may improve the antenatal identification of abnormal fetal growth.
authors.affiliation: a Department of Obstetrics and Gynecology , Università Roma Tor Vergata , Roma , Italy .
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rizzo
authors.affiliation: b Department of Obstetrics and Gynecology , Università of Brescia , Italy .
authors.forename: Federico
authors.initials: F
authors.lastname: Prefumo
authors.affiliation: c Department of Obstetrics and Gynecology , Università of Milan Buzzi Children's Hospital , Italy .
authors.forename: Enrico
authors.initials: E
authors.lastname: Ferrazzi
authors.affiliation: b Department of Obstetrics and Gynecology , Università of Brescia , Italy .
authors.forename: Cristina
authors.initials: C
authors.lastname: Zanardini
authors.affiliation: c Department of Obstetrics and Gynecology , Università of Milan Buzzi Children's Hospital , Italy .
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Martino
authors.affiliation: d Department of Obstetrics and Gynecology , Università of Milan 'L. Mangiagalli', Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico , Milan , Italy , and.
authors.forename: Simona
authors.initials: S
authors.lastname: Boito
authors.affiliation: a Department of Obstetrics and Gynecology , Università Roma Tor Vergata , Roma , Italy .
authors.forename: Elisa
authors.initials: E
authors.lastname: Aiello
authors.affiliation: e Department of Obstetrics and Gynecology , Università of Parma , Italy.
authors.forename: Tullio
authors.initials: T
authors.lastname: Ghi
mesh_terms: D001699:Biometry; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D005865:Gestational Age; D057238:Growth Charts; D006801:Humans; D007558:Italy; D008297:Male; D011247:Pregnancy; D012016:Reference Values; D012044:Regression Analysis; D012737:Sex Factors; D016216:Ultrasonography, Prenatal
keywords: Customized growth chart; fetal biometry; gender difference; quantile regression