title: Characterizing maternal glycemic control: a more informative approach using semiparametric regression.
abstract: OBJECTIVE
  To characterize glucose concentrations measured throughout pregnancy in women with type 1 diabetes using semiparametric regression analysis to examine the gestational time-specific association with fetal outcome.
  
  
  METHODS
  We conducted a secondary analysis of data from an interdisciplinary program of diabetes in pregnancy of women with type 1 diabetes. Semiparametric regression was used to characterize glucose concentrations measured using reflectance meters throughout pregnancy by examining the time-specific association of maternal glucose with delivery of a large for gestational age (LGA) baby.
  
  
  RESULTS
  The optimal model demonstrated that time-specific differences in glycemic profiles of mothers who had LGA versus AGA babies changed at various rates across gestation (p = 0.0007). AGA glucose profiles exceeded LGA profiles in the first trimester and mid pregnancy; conversely LGA glucose profiles exceeded AGA profiles initially during the third trimester. Differences were based on examination of 95% simultaneous confidence bands.
  
  
  CONCLUSIONS
  Semiparametric regression techniques enabled synchronous inclusion of all glucose concentrations using multi-step modeling. We identified specific periods of gestation where maternal glucose concentrations differ for the LGA and AGA developing fetus, with greatest distinctions appearing in first and third trimesters. Novel statistical approaches that examine time-specific behavior garner insight into longitudinal assessment of maternal glycemic control.
authors.affiliation: Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45208, USA. Rhonda.VanDyke@cchmc.org
authors.forename: Rhonda
authors.initials: R
authors.lastname: Vandyke
authors.forename: Yan
authors.initials: Y
authors.lastname: Ren
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Sucharew
authors.forename: Menachem
authors.initials: M
authors.lastname: Miodovnik
authors.forename: Barak
authors.initials: B
authors.lastname: Rosenn
authors.forename: Jane C
authors.initials: JC
authors.lastname: Khoury
mesh_terms: D001724:Birth Weight; D001786:Blood Glucose / Q000032:analysis*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D005260:Female; D005320:Fetal Macrosomia / Q000097:blood; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000097:blood*; D012044:Regression Analysis
chemical_list: D001786:Blood Glucose