title: Placental Growth during Normal Pregnancy - A Magnetic Resonance Imaging Study.
abstract: OBJECTIVE
  To investigate normal human placental growth longitudinally throughout the second and third trimesters using MRI.
  
  
  METHODS
  Twenty normal, first-time singleton pregnancies were scanned 7 times between the 14th and 38th week of gestation, at 4-week intervals, using MRI. Placental volumes were measured in both sagittal and transversal slices. All placentas were weighed after delivery to make a comparative study.
  
  
  RESULTS
  Sixteen of the 20 women had increasing placental volumes from the 14th to 38th week of gestation. The 6th and 7th scan showed that 4 women had placentas of the same size. The mean placental volume increases linearly from the 14th till the 38th week of gestation, with a constant mean growth rate of 29.97 ml/week. The median placental volume extrapolated to delivery was to 856 ml (range 602-1,050 ml). The median weight of the exsanguinated placenta after delivery was 640 g (range 500-787 g). All pregnancies were carried to term, resulting in the delivery of healthy infants with good correlation between placental size and birth weight (R = 0.56, p = 0.009).
  
  
  CONCLUSIONS
  Placental growth was measured systematically in a longitudinal study through the second and third trimesters using MRI. MRI provides a safe and feasible method to measure placental growth. The mean placental growth was linear throughout the second and third trimesters.
authors.affiliation: Department of Obstetric and Gynecology, Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Lasse
authors.initials: L
authors.lastname: Langhoff
authors.forename: Lene
authors.initials: L
authors.lastname: Grønbeck
authors.forename: Sebastian
authors.initials: S
authors.lastname: von Huth
authors.forename: Anna
authors.initials: A
authors.lastname: Axelsson
authors.forename: Connie
authors.initials: C
authors.lastname: Jørgensen
authors.forename: Carsten
authors.initials: C
authors.lastname: Thomsen
authors.forename: Niels
authors.initials: N
authors.lastname: Vejlstrup
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D036801:Parturition; D010920:Placenta / Q000000981:diagnostic imaging* / Q000502:physiology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third
keywords: MRI; Obstetric; Placenta; Pregnancy