title: A nested case-control study of first-trimester maternal vitamin D status and risk for spontaneous preterm birth.
abstract: We assessed if first-trimester vitamin D deficiency is more prevalent in women who experienced a spontaneous preterm birth compared with women who delivered at term. We conducted a nested case-control study of pregnant women who had previously given blood for first-trimester combined screening for trisomy 21 and subsequently delivered at a tertiary hospital between November 2004 and July 2009. From an overall cohort of 4225 women, 40 cases of spontaneous preterm birth (≥ 23 (0/7) and ≤ 34 (6/7) weeks) were matched by race/ethnicity with 120 women delivering at term (≥ 37 (0/7) weeks) with uncomplicated pregnancies. Banked maternal serum was used to measure maternal 25-hydroxyvitamin D [25(OH)D]. The prevalence of first-trimester maternal vitamin D deficiency [25(OH)D < 50 nmol/L] was comparable among women who subsequently delivered preterm compared with controls (7.5% versus 6.7%, P  = 0.90). The median 25(OH)D level for all subjects was 89 nmol/L (interquartile range, 73 to 106 nmol/L). Seventy-three percent (117/160) of the cohort had sufficient vitamin D levels [25(OH)D ≥ 75 nmol/L]. In a cohort of pregnant women with mostly sufficient levels of first-trimester serum 25(OH)D, vitamin D deficiency was not associated with spontaneous preterm birth.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Gilling School of Global Pulic Health, University of North Carolina, Chapel Hill, North Carolina 27599-7516, USA. abaker2@med.unc.edu
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Baker
authors.forename: Sina
authors.initials: S
authors.lastname: Haeri
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
authors.forename: Alison M
authors.initials: AM
authors.lastname: Stuebe
authors.forename: Kim A
authors.initials: KA
authors.lastname: Boggess
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood*; D011261:Pregnancy Trimester, First / Q000097:blood*; D047928:Premature Birth / Q000097:blood / Q000209:etiology*; D015995:Prevalence; D018709:Statistics, Nonparametric; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D