title: A longitudinal study of plasma levels of soluble fms-like tyrosine kinase 1 (sFlt1), placental growth factor (PlGF), sFlt1: PlGF ratio and vascular endothelial growth factor (VEGF-A) in normal pregnancy.
abstract: OBJECTIVE
  To describe plasma levels of angiogenic (PlGF, VEGF-A) and anti-angiogenic (sFlt1) factors as well as the sFlt1:PlGF ratio throughout normal pregnancy and postpartum.
  
  
  METHODS
  Longitudinal prospective study.
  
  
  METHODS
  One outpatient antenatal clinic in Uppsala, Sweden.
  
  
  METHODS
  Thirty-seven healthy women with normal pregnancies and normal neonatal outcome were included.
  
  
  METHODS
  Blood samples were collected from each woman at least six times. Plasma levels of sFlt1, PlGF and VEGF-A were measured using commercially available ELISA kits.
  
  
  METHODS
  Median plasma levels, the 25th to the 75th percentile and the average change per gestational week of sFlt1, PlGF and the sFlt1:PlGF ratio.
  
  
  RESULTS
  sFlt1 levels were relatively constant until weeks 29-30, when they increased, reaching a peak at week 40. An increase of 643pg/ml per week was observed from weeks 30 to 40. Postpartum levels were low. PlGF increased by 16pg/ml per week from early pregnancy until weeks 29-30 and thereafter decreased by 14pg/ml per week until week 40. The sFlt1:PlGF ratio decreased from weeks 9-12, was constantly low from weeks 19-20 to 37-38 and then increased to weeks 39-40. VEGF-A was detectable in only 8% of the samples during pregnancy and in 64% postpartum.
  
  
  CONCLUSIONS
  This longitudinal study demonstrates how sFlt1, PlGF and the sFlt1:PlGF ratio fluctuate throughout normal pregnancy and postpartum and may serve as a reference against which these factors can be studied in complicated pregnancies. VEGF-A levels were more often detectable postpartum.
authors.affiliation: Department of Women's and Children's Health, Obstetrics and Gynecology, Uppsala University, Uppsala, Sweden. maria.palm@kbh.uu.se
authors.forename: Maria
authors.initials: M
authors.lastname: Palm
authors.forename: Samar
authors.initials: S
authors.lastname: Basu
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: Lisa
authors.initials: L
authors.lastname: Wernroth
authors.forename: Helena
authors.initials: H
authors.lastname: Åkerud
authors.forename: Ove
authors.initials: O
authors.lastname: Axelsson
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D000072483:Placenta Growth Factor; D011247:Pregnancy / Q000097:blood*; D011257:Pregnancy Proteins / Q000097:blood*; D012016:Reference Values; D042461:Vascular Endothelial Growth Factor A / Q000097:blood*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000097:blood*
chemical_list: C000608036:PGF protein, human; D011257:Pregnancy Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D000072483:Placenta Growth Factor; C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1