Cord blood vitamin D status and neonatal outcomes in a birth cohort in Quebec, Canada
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Some evidence suggests that low maternal vitamin D status adversely affects perinatal health but few studies have examined cord blood vitamin D status. This project aimed to determine the association between the cord blood concentration of 25-hydroxyvitamin D [25(OH)D] and neonatal outcomes.
A nested case–control study was conducted in Quebec City, Canada from 2005 to 2010. Included were 83 cases of low birthweight (LBW; <2500 g), 301 cases of small for gestational age (SGA; <10th percentile), 223 cases of preterm birth (PTB; <37 weeks’ gestation), and 1027 controls. Levels of 25(OH)D were determined by chemiluminescence immunoassay. Adjusted odds ratios (OR) and 95 % confidence intervals (CI) were estimated with logistic regression.
Cord blood [25(OH)D] <50 nmol/L was associated with a lower risk of LBW compared to [25(OH)D] ≥75 nmol/L (OR 0.47 95 % CI 0.23–0.97). For 25(OH)D levels 50–75 nmol/L, a significant association was not demonstrated (OR 0.58, 95 % CI 0.34–1.01). No significant associations were observed between [25(OH)D] and either SGA or PTB after adjustment.
Although our findings suggest that [25(OH)D] <50 nmol/L is associated with reduced risk of having a LBW infant, prenatal vitamin D recommendations require an examination of the literature that considers the full spectrum of maternal and neonatal outcomes.
Keywords25-Hydroxyvitamin D Low birth weight Small for gestational age Preterm birth Nested case–control study
The Canadian Institutes of Health Research provided funding for this study (Operating Grant 244113). We acknowledge Madonna Achkar and Sherry Agellon from Dr. Hope Weiler’s laboratory at McGill University for their contribution in analyzing the cord blood samples. We thank Nathalie Bernard and Mylène Badeau from the Quebec City team for their professional assistance with the project, and our research nurses for the recruitment of participants and retrieval of data from the medical records. We acknowledge Anne Spencer for her assistance in data management and supplementary analyses. We also thank all study participants.
Compliance with ethical standards
Conflict of interest
The authors do not have a financial relationship with the organization that sponsored this research. The authors had full control of all primary data and agree to allow the Journal to review their data if requested.
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