title: Umbilical cord plasma interleukin-6 and fetal growth restriction in preeclampsia: a prospective study in Norway.
abstract: OBJECTIVE
  To study the association between umbilical plasma levels of interleukin-6 (IL-6) in relation to fetal growth in subgroups of preeclampsia, and in control pregnancies.
  
  
  METHODS
  Umbilical cord plasma was collected from 12,804 consecutive births. A total of 271 singleton cases of preeclampsia were identified, and classified as mild or severe, and as disease with early or late onset. As controls, 611 singleton pregnancies without preeclampsia were selected, and the ratio between observed and expected birth weight was used as a measure of fetal growth. In the analysis, we also included maternal smoking during pregnancy. Umbilical cord plasma IL-6 concentration was measured with an IL-6 bioassay. Comparing controls with subgroups of preeclampsia (severe and early onset), this study had a statistical power of 90% to detect a difference in cord IL-6 of 10 pg/mL.
  
  
  RESULTS
  In severe preeclampsia, cord plasma IL-6 concentration was lower than among controls (P <.001), and there was a sharp decrease in cord plasma IL-6 with decreasing birth weight ratio (P trend <.001). By further dividing the preeclampsia group into early or late onset, the strong association between low IL-6 levels and low birth weight ratio appeared to be present mainly in early-onset disease. These results were not confounded by maternal smoking.
  
  
  CONCLUSIONS
  Restricted fetal growth related to preeclampsia is associated with reduced umbilical cord plasma IL-6 concentration in cases with early-onset disease. In these cases, fetal growth restriction could be mediated by impaired trophoblast function.
authors.affiliation: Institute of Cancer Research and Molecular Biology, the Institute of Community Medicine and General Practice, Norwegian University of Science and Technology, Trondheim, Norway. ronnaug.odegard@medisin.ntnu.no
authors.forename: R A
authors.initials: RA
authors.lastname: Ødegård
authors.forename: L J
authors.initials: LJ
authors.lastname: Vatten
authors.forename: S T
authors.initials: ST
authors.lastname: Nilsen
authors.lastname: Salvesen KA
authors.forename: H
authors.initials: H
authors.lastname: Vefring
authors.forename: R
authors.initials: R
authors.lastname: Austgulen
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005317:Fetal Growth Retardation / Q000097:blood* / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D015850:Interleukin-6 / Q000097:blood*; D011225:Pre-Eclampsia / Q000097:blood / Q000150:complications*; D011247:Pregnancy; D011446:Prospective Studies; D012907:Smoking
chemical_list: D015850:Interleukin-6