Healthy Pregnancy Cohort and Vitamin D Levels

Between 2006 and 2011 the CANDLE study enrolled 1503 healthy women during their second trimester of pregnancy [27 (link),30 (link)]. As we reported previously in Nutrients [30 (link)], inclusion criteria included women ages 16 to 40 years, residents of Shelby County TN, ability to speak and understand English, and 16–28 weeks of gestation with singleton pregnancy. Informed consent was given by participants 18 years or older, and assent was given by those 16–17.9 years, with consent provided by their legally authorized representative prior to enrollment.
Exclusion criteria included: an existing chronic disease requiring medication (e.g., hypertension, type 1 or type 2 diabetes mellitus, sickle cell disease or trait, renal disease, hepatitis, lupus erythematous, scleroderma, pulmonary disease, heart disease, human immunodeficiency virus); pregnancy complications (including maternal red cell alloimmunization though Rh factor incompatibility was permitted, prolapsed or ruptured membranes, oligohydramnios, complete placenta previa); and not intending to deliver at one of four participating hospitals [30 (link)]. The study was conducted in accordance with the Helsinki Declaration and approved by the Institutional Review Board of The University of Tennessee Health Science Center. Of the 1455 live births, 1020 mother-child dyads completed the 2-year clinic exam and had mothers who provided blood for 25(OH)D levels during the second trimester. Figure 1 outlines the participants available for this study.