Seasonal Variation in Solar Ultra Violet Radiation and Early Mortality in Extremely Preterm Infants

Abstract Background Vitamin D production during pregnancy promotes fetal lung development, a major determinant of infant survival after preterm birth. Because vitamin D synthesis in humans is regulated by solar ultraviolet B (UVB) radiation, we hypothesized that seasonal variation in solar UVB doses during fetal development would be associated with variation in neonatal mortality rates. Methods This cohort study included infants born alive with gestational age (GA) between 23 and 28 weeks gestation admitted to a neonatal unit between 1996 and 2010. Three infant cohort groups were defined according to increasing intensities of solar UVB doses at 17 and 22 weeks gestation. The primary outcome was death during the first 28 days after birth. Results Outcome data of 2,319 infants were analyzed. Mean birth weight was 830 ± 230 g and median gestational age was 26 weeks. Mortality rates were significantly different across groups (p = 0.04). High-intensity solar UVB doses were associated with lower mortality when compared with normal intensity solar UVB doses (hazard ratio: 0.70; 95% confidence interval: 0.54–0.91; p = 0.01). Conclusion High-intensity solar UVB doses during fetal development seem to be associated with risk reduction of early mortality in preterm infants. Prospective studies are needed to validate these preliminary findings.

[1]  C. Wagner,et al.  Post-hoc comparison of vitamin D status at three timepoints during pregnancy demonstrates lower risk of preterm birth with higher vitamin D closer to delivery , 2015, The Journal of Steroid Biochemistry and Molecular Biology.

[2]  P. Zhu,et al.  Maternal vitamin D deficiency during pregnancy elevates the risks of small for gestational age and low birth weight infants in Chinese population. , 2015, The Journal of clinical endocrinology and metabolism.

[3]  R. Lucas,et al.  Vitamin D in Fetal Development: Findings From a Birth Cohort Study , 2015, Pediatrics.

[4]  Shuqin Wei.  Vitamin D and pregnancy outcomes , 2014, Current opinion in obstetrics & gynecology.

[5]  P. Sidebotham,et al.  Understanding why children die in high-income countries , 2014, The Lancet.

[6]  S. Carlson,et al.  Typical Prenatal Vitamin D Supplement Intake Does Not Prevent Decrease of Plasma 25-Hydroxyvitamin D at Birth , 2014, Journal of the American College of Nutrition.

[7]  C. Wagner,et al.  Vitamin D supplementation during pregnancy: Double‐blind, randomized clinical trial of safety and effectiveness , 2011, Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research.

[8]  Shelley Gorman,et al.  Vitamin D deficiency causes deficits in lung function and alters lung structure. , 2011, American journal of respiratory and critical care medicine.

[9]  M. Walsh,et al.  Intercenter Differences in Bronchopulmonary Dysplasia or Death Among Very Low Birth Weight Infants , 2011, Pediatrics.

[10]  O. Engelsen.  The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status , 2010, Nutrients.

[11]  L. Waller,et al.  Seasonality of Birth and Implications for Temporal Studies of Preterm Birth , 2009, Epidemiology.

[12]  Carlos A Camargo,et al.  Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. , 2009, Archives of internal medicine.

[13]  William J Olds,et al.  In vitro model of vitamin D3 (cholecalciferol) synthesis by UV radiation: dose-response relationships. , 2008, Journal of photochemistry and photobiology. B, Biology.

[14]  L. Bodnar,et al.  The prevalence of preterm birth and season of conception. , 2008, Paediatric and perinatal epidemiology.

[15]  R. McKenzie,et al.  Seasonal variation in vitamin D levels in the Canterbury, New Zealand population in relation to available UV radiation. , 2007, The New Zealand medical journal.

[16]  S. Peleg,et al.  Regulation of human pulmonary surfactant protein gene expression by 1alpha,25-dihydroxyvitamin D3. , 2005, American journal of physiology. Lung cellular and molecular physiology.

[17]  A. Barnett,et al.  The association between birth weight, season of birth and latitude , 2005, Annals of human biology.

[18]  T. M. Nguyen,et al.  Evidence for a vitamin D paracrine system regulating maturation of developing rat lung epithelium. , 1996, The American journal of physiology.

[19]  M. Holick,et al.  Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. , 1988, The Journal of clinical endocrinology and metabolism.

[20]  R. Nugent,et al.  Seasonal patterns in perinatal mortality and preterm delivery. , 1983, American journal of epidemiology.

[21]  T. Oppé,et al.  Vitamin D deficiency. , 1979, British medical journal.

[22]  R. McKenzie,et al.  UV Radiation: Balancing Risks and Benefits † , 2009, Photochemistry and photobiology.

[23]  L. Monte,et al.  [Bronchopulmonary dysplasia]. , 2005, Jornal de pediatria.