title: Exploring sexual dimorphism in placental circulation at 22-24 weeks of gestation: A cross-sectional observational study.
abstract: Placental blood flow is closely associated with fetal growth and wellbeing. Recent studies suggest that there are differences in blood flow between male and female fetuses. We hypothesized that sexual dimorphism exists in fetal and placental blood flow at 22-24 weeks of gestation.
  
  
  
  This was a prospective cross-sectional study of 520 healthy pregnant women. Blood flow velocities of the middle cerebral artery (MCA), umbilical artery (UA), umbilical vein (UV) and the uterine arteries (UtA) were measured using Doppler ultrasonography. UV and UtA diameters were measured using two-dimensional ultrasonography and power Doppler angiography. Volume blood flows (Q) of the UV and UtA were calculated. Maternal haemodynamics was assessed with impedance cardiography. UtA resistance (Ruta) was computed as MAP/Quta.
  
  
  
  UA PI was significantly (p = 0.008) higher in female fetuses (1.19 ± 0.15) compared with male fetuses (1.15 ± 0.14). MCA PI, cerebro-placental ratio (MCA PI/UA PI), Quv,UtA PI, Qutaand Rutawere not significantly different between groups. At delivery, the mean birth weight and placental weight of female infants (3504 g and 610 g) were significantly (p = 0.0005 and p = 0.039) lower than that of the male infants (3642 g and 634 g).
  
  
  
  We have demonstrated sexual dimorphism in UA PI, a surrogate for placental vascular resistance, at 22-24 weeks of gestation. Therefore, it would be useful to know when this difference emerges and whether it translates into blood flow differences that may impact upon the fetal growth trajectory.
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway and Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway. Electronic address: Christian.Widnes@unn.no.
authors.forename: Christian
authors.initials: C
authors.lastname: Widnes
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway and Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway.
authors.forename: Kari
authors.initials: K
authors.lastname: Flo
authors.affiliation: Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway and Department of Obstetrics and Gynaecology, University Hospital of North Norway, Tromsø, Norway; Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden.
authors.forename: Ganesh
authors.initials: G
authors.lastname: Acharya
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D021041:Placental Circulation / Q000502:physiology*; D011247:Pregnancy; D012727:Sex Characteristics; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging*; D055988:Uterine Artery / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Doppler; Placental function; Sex differences; Umbilical artery; Umbilical vein; Uterine artery