title: The influence of maternal hematocrit on placental development from the first to the second trimesters of pregnancy.
abstract: OBJECTIVE
  To study the influence of maternal hematocrit (Ht) and hemoglobin (Hb) levels on placental size and growth in the first and mid-second trimesters of pregnancy.
  
  
  METHODS
  This was a prospective study performed at the fetal medicine unit of a university hospital. One hundred and eighty-one women with a singleton pregnancy were recruited at 11-14 weeks' gestation. For each case three scans of the placenta were performed, the first at recruitment and the following two at 3-week intervals. The volume of the placenta was measured at each visit using a three-dimensional ultrasound scanner. The maternal Hb and Ht were measured within 2 weeks of the first scan.
  
  
  RESULTS
  The placental growth during the second trimester was inversely related to the Ht levels (r = -0.29, P = 0.001). It was also related to the Hb level (r = -0.20, P = 0.021). An increase of 0.1 units of Ht was associated with 38% less growth of the placenta (95% confidence interval: 18-54% less growth).
  
  
  CONCLUSIONS
  This study demonstrates the effects of maternal environment on placental growth. Our data suggest that the levels of Ht appear to affect the placental growth during the second trimester. Further studies on the factors that regulate placental growth are needed to elucidate the pathophysiology of these interactions and their effect on pregnancy outcome.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Royal Free Hospital, Pond Street, London, UK.
authors.forename: G D
authors.initials: GD
authors.lastname: Michailidis
authors.forename: R W
authors.initials: RW
authors.lastname: Morris
authors.forename: A
authors.initials: A
authors.lastname: Mamopoulos
authors.forename: P
authors.initials: P
authors.lastname: Papageorgiou
authors.forename: D L
authors.initials: DL
authors.lastname: Economides
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D010920:Placenta / Q000000981:diagnostic imaging; D010929:Placentation; D011247:Pregnancy / Q000502:physiology*; D011261:Pregnancy Trimester, First / Q000502:physiology; D011262:Pregnancy Trimester, Second / Q000502:physiology; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal
chemical_list: D006454:Hemoglobins