title: Maternal glomerular filtration rate in pregnancy and fetal size.
abstract: BACKGROUND
  The relationship of maternal glomerular filtration rate (GFR) in pregnancy to fetal size needs to be better characterized as it impacts an ongoing debate about confounding effect of maternal GFR in investigations of important environmental contaminants. We aimed to characterize the size of the association between maternal GFR and infant birth weight.
  
  
  METHODS
  A sub-cohort of 953 selected women (470 women with and 483 women without preeclampsia) in the Norwegian Mother and Child Cohort (MoBa), recruited during 2003-2007 were analyzed. GFR in the second trimester was estimated based on plasma creatinine. Birth weight was ascertained from the Medical Birth Registry of Norway. Multivariate linear regression was used to evaluate the association between maternal GFR in second trimester (estimated by the Cockroft-Gault [GFR-CG] and the modification of diet in renal disease [GFR-MDRD] formulas) and infant birth weight. Partial correlation coefficients were also calculated.
  
  
  RESULTS
  Maternal GFR-CG (β: 0.73 g/ml/min, p = 0.04) and GFR-MDRD (β: 0.83 g/ml/min, p = 0.04) were associated with infant birth weight in models adjusted for maternal weight in kilograms, preeclampsia, and gestational age at delivery (days). Partial correlation coefficients for the association between infant birth weight and GFR were 0.07 for both formulas. Although the birth weight-GFR association was stronger among the women with preeclampsia, the difference from women without preeclampsia was not statistically significant.
  
  
  CONCLUSIONS
  These data support an association between GFR during pregnancy and infant birth weight, and indicate that GFR may confound selected epidemiologic associations.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Department of Clinical Sciences, University of Bergen, Bergen, Norway; Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Nils-Halvdan
authors.initials: NH
authors.lastname: Morken
authors.affiliation: Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Travlos
authors.affiliation: Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America.
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Wilson
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Merete
authors.initials: M
authors.lastname: Eggesbø
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina, United States of America.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Longnecker
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D005260:Female; D020567:Fetal Weight; D005865:Gestational Age; D005919:Glomerular Filtration Rate; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009664:Norway; D011225:Pre-Eclampsia / Q000503:physiopathology; D011247:Pregnancy; D055815:Young Adult
chemical_list: D003404:Creatinine