title: Maternal BMI Associations with Maternal and Cord Blood Vitamin D Levels in a North American Subset of Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study Participants.
abstract: OBJECTIVE
  Obesity in pregnancy may be associated with reduced placental transfer of 25-hydroxyvitamin D (25-OHD). The objective of this study was to examine associations between maternal BMI and maternal and cord blood levels of 25-OHD in full term neonates born to a single racial cohort residing at similar latitude. Secondary objectives were to examine associations between maternal glucose tolerance with maternal levels of 25-OHD and the relationship between cord blood 25-OHD levels and neonatal size.
  
  
  METHODS
  This study was conducted among participants of the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) Study meeting the following criteria: residing at latitudes 41-43°, maternal white race, and gestational age 39-41 weeks. Healthy pregnant women underwent measures of height, weight, and a 75-g fasting oral glucose tolerance test (OGTT) at approximately 28 weeks gestation. Maternal and cord blood sera were analyzed for total 25-OHD by HPLC tandem mass spectrometry. Statistical analyses included ANOVA and linear regression models.
  
  
  RESULTS
  Maternal and cord blood (N = 360) mean levels (sd) of 25-OHD were 37.2 (11.2) and 23.4 (9.2) ng/ml, respectively, and these levels were significantly different among the 3 field centers (ANOVA p< 0.001). Maternal serum 25-OHD was lower by 0.40 ng/ml for BMI higher by 1 kg/m2 (p<0.001) in an adjusted model. Maternal fasting plasma glucose, insulin sensitivity, and presence of GDM were not associated with maternal serum 25-OHD level when adjusted for maternal BMI. Cord blood 25-OHD was lower by 0.26 ng/ml for maternal BMI higher by 1 kg/m2 (p<0.004). With adjustment for maternal age, field center, birth season and maternal serum 25-OHD, the association of cord blood 25-OHD with maternal BMI was attenuated. Neither birth weight nor neonatal adiposity was significantly associated with cord blood 25-OHD levels.
  
  
  CONCLUSIONS
  These results suggest that maternal levels of 25-OHD are associated with maternal BMI. The results also suggest that interpretation of neonatal 25-OHD levels may need to incorporate specific maternal factors in addition to season of birth and latitude.
authors.affiliation: Ann & Robert H. Lurie Children's Hospital of Chicago, Division of Endocrinology; 2. Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.|Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
authors.forename: Jami L
authors.initials: JL
authors.lastname: Josefson
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
authors.forename: Anna
authors.initials: A
authors.lastname: Reisetter
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
authors.forename: Denise M
authors.initials: DM
authors.lastname: Scholtens
authors.affiliation: Ann & Robert H. Lurie Children's Hospital of Chicago, Division of Kidney Diseases, Chicago, Illinois, United States of America.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Price
authors.affiliation: Department of Medicine-Endocrinology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
authors.forename: Boyd E
authors.initials: BE
authors.lastname: Metzger
authors.affiliation: Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.|Ann & Robert H. Lurie Children's Hospital of Chicago, Division of Kidney Diseases, Chicago, Illinois, United States of America.
authors.forename: Craig B
authors.initials: CB
authors.lastname: Langman
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000150:complications*; D007231:Infant, Newborn; D016014:Linear Models; D009656:North America; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood*; D011256:Pregnancy Outcome; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D