Effect of Month of Birth on the Risk of Developing Psoriasis

  • Ana Martins Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
  • Andreia Bettencourt Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal; Laboratório de Imunogenética, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
  • Tiago Torres Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal; Consulta de Psoríase do Serviço de Dermatologia do Centro Hospitalar e Universitário do Porto, Porto, Portugal
Keywords: Psoriasis, Risk Factors Seasons, Sunlight, Ultraviolet Rays, Vitamin D


Introduction: Psoriasis is an immunemediated dermatosis characterized by chronic inflammation, abnormal proliferation and aberrant differentiation of keratinocytes, hyperplastic blood vessels and infiltration of inflammatory cells. Psoriasis is a multifactorial disease and is influenced by genetics and epigenetic modifications that can be triggered by environmental factors. Climate and sun exposure may affect psoriasis prevalence and the ultraviolet radiation is a useful treatment. Our objective was to evaluate the relationship between the month of birth and the risk of developing psoriasis.

Methods: The monthly distribution of births of patients with psoriasis (n = 755) was compared to that of a control population, comprised by Portuguese individual born during the same period and from the same region (n = 6 560 032).

Results: Birth rate of psoriasis patients decreased in October (OR 0.74; 95% CI 0.55 – 0.99; p 0.041). After Bonferroni correction and after grouping the months by trimesters, no statistical significant differences were found.

Conclusion: Our results may be related to the particular meteorological characteristics of Portugal that may lead to stabilization of the vitamin D synthesis during the whole year. The perception of the environmental influence on the development of a specific pathology is very important because it allows the establishment of preventive measures that will reduce disease incidence. 


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Deng Y, Chang C, Lu Q. The inflammatory response in psoriasis: a comprehensive. Clin Rev Allergy Immunol. 2016: 50:377-89.

Boehncke WH, Schön MP. Psoriasis. Lancet.2015;386: 983-94.

Torres T, Sales R, Vasconcelos C, Selores M. Psoriasis and cardiovascular disease. Acta Med Port.; 26:601-7.

Ritchlin CT, Kavanaugh A, Gladman DD, Mease PJ, Helliwell P, Boehncke WH, et al. Treatment recommendations for psoriatic arthritis. Ann Rheum Dis. 2009; 68:1387-94.

Balato N, Di Costanzo L, Patruno C, Patrì A, Ayala F. Effect of weather and environmental factors on the clinical course of psoriasis. Occup Environ Med. 2013; 70:600.

Juzeniene A, Grigalavicius M, Juraleviciute M, Grant WB. Phototherapy and vitamin D. Clin Dermatol. 2016;


Mattozzi C, Paolino G, Richetta AG, Calvieri S. Psoriasis, vitamin D and the importance of the cutaneous barrier’s integrity: An update. J Dermatol.2016; 43:507-14.

Disanto G, Chaplin G, Morahan JM, Giovannoni G, Hyppönen E, Ebers GC, et al. Month of birth, vitamin

D and risk of immune-mediated disease: a case control study. BMC Med.2012; 10:69.

Orgaz-Molina J, Buendía-Eisman A, Arrabal-Polo MA, Ruiz JC, Arias-Santiago S. Deficiency of serum concentration of 25-hydroxyvitamin D in psoriatic patients: a case-control study. J Am Acad Dermatol. 2012:


Ricceri F, Pescitelli L, Tripo L, Prignano F. Deficiency of serum concentration of 25- hydroxyvitamin D correlates with severity of disease in chronic plaque psoriasis. J Am Acad Dermatol.2013; 68:511-2.

Khoo AL, Chai LY, Koenen HJ, Sweep FC, Joosten I, Netea MG, et al. Regulation of cytokine responses by

seasonality of vitamin D status in healthy individuals. Clin Exp Immunol.2011; 164:72-9.

Gorman S, Judge MA, Burchell JT, Turner DJ, Hart PH. 1,25-dihydroxyvitamin D3 enhances the ability of

transferred CD4+ CD25+ cells to modulate T helper type 2-driven asthmatic responses. Immunology.2010;


Wang TT, Nestel FP, Bourdeau V, Nagai Y, Wang Q, Liao J, et al. Cutting edge: 1,25-dihydroxyvitamin D3 is a direct inducer of antimicrobial peptide gene expression. J Immunol. 2004; 173:2909-12.

Søyland E, Heier I, Rodríguez-Gallego C, Mollnes TE, Johansen FE, Holven KB, et al. Sun exposure induces rapid immunological changes in skin and peripheral blood in patients with psoriasis. Br J Dermatol. 2011; 164:344-55.

Grytten N, Torkildsen Ø, Aarseth JH, Benjaminsen E, Celius EG, Dahl OP, et al. Month of birth as a latitude-dependent risk factor for multiple sclerosis in Norway. Mult Scler J.2013; 19:1028-34.

Torkildsen O, Aarseth J, Benjaminsen E, Celius E, Holmøy T, Kampman MT, et al. "onth of birth and risk of

multiple sclerosis: confounding and adjustments. Ann Clin Transl Neurol. 2014;1:141-4.

Menni C, Lowell WE, Bentzen J, Bergamaschi R, Martinelli Boneschi F, et al. Short and long term variation in ultraviolet radiation and multiple sclerosis. Int J Environ Res Public Health.2012; 9:685-97.

Bayes HK, Weir CJ, O’Leary C. Timing of birth and risk of multiple sclerosis in the Scottish population. Eur Neurol. 2010; 63:36-40.

Villar-Quiles RN, Matías-Guiu JA, Ortega G, González-Suárez I, Oreja-Guevara C, Matías-Guiu J. Analysis

of the relationship between the month of birth and risk of multiple sclerosis in a Spanish population. Eur Neurol. 2016; 76:202-9.

Barros P, de Sá JM, Sá MJ. Month of birth and risk of multiple sclerosis in a Portuguese population. Clin Neurol Neurosurg.2013; 115:1762-5.

Al-Garawi A, Carey VJ, Chhabra D, Mirzakhani H, Morrow J, Lasky-Su J, et al. The role of vitamin D in the transcriptional program of human pregnancy. PLoS One. 2016; 11:e0163832.

Munger KL, Åivo J, Hongell K, Soilu-Hänninen M, Surcel HM, Ascherio A. Vitamin D status during pregnancy and risk of multiple sclerosis in offspring of women in the Finnish maternity cohort. JAMA Neurol. 2016; 73:515-9.

Sharief S, Jariwala S, Kumar J, Muntner P, Melamed ML. Vitamin D levels and food and environmental allergies in the United States: Results from the National Health and Nutrition Examination Survey. J Allergy Clin Immunol. 2011; 127:1195-1202.

Chiu CY, Huang SY, Peng YC, Tsai MH, Hua MC, Yao TC, et al. Maternal vitamin D levels are inversely related to allergic sensitization and atopic diseases in early childhood. Pediatr Allergy Immunol. 2015; 25:337-43.

Bunyavanich S, Rifas-Shiman SL, Platts-Mills TA, Workman L, Sordillo JE, Camargo CA Jr, et al. Prenatal, perinatal, and childhood vitamin D exposure and their association with childhood allergic rhinitis and allergic

sensitization. J Allergy Clin Immunol. 2016; 137:1063-70.

Erkkola M, Kaila M, Nwaru BI, Kronberg-Kippilä C, Ahonen S, Nevalainen J, et al. Maternal vitamin D intake during pregnancy is inversely associated with asthma and allergic rhinitis in 5-year-old children. Clin Exp Allergy. 2009; 39:875-82.

Kun Z, Andrew JO, Prue H, Merci K, Jenny M, Stephen L, et al. Maternal vitamin D status during pregnancy and bone mass in offspring at 20 years of age: a prospective cohort study. J Bone Miner Res. 2014; 29:1088-95.

Javaid MK, Crozier SR, Harvey NC, Gale CR, Dennison EM, Boucher BJ, et al. Maternal vitamin D status during pregnancy and childhood bone mass at age 9 years: a longitudinal study. Lancet. 2006; 367: 36-43.

Takiishi T, Gysemans C, Bouillon R, Mathieu C. Vitamin D and diabetes. Endocrinol Metab Clin North Am.

; 39:419-46.

Brekke HK, Ludvigsson J. Vitamin D supplementation and diabetes-related autoimmunity. Pediatr Diabetes. 2007; 8:11-4.

Zipitis CS, Akobeng AK. Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis. Arch Dis Child. 2008; 93:512-7.

Magnus MC, Stene LC, Håberg SE, Nafstad P, Stigum H, London SJ, et al. Prospective study of maternal mid-pregnancy 25-hydroxyvitamin D level and early childhood respiratory disorders. Paediatr Perinat Epidemiol. 2013; 27:532-41.

Dirnagl U, Lauritzen M. Fighting publication bias: introducing the negative results section. J Cereb Blood Flow Metab, 2010; 30: 1263-4.

Dawodu A, Wagner CL. Mother-child vitamin d deficiency: an international perspective. Arch Dis Child. 2007; 92:737-40.

O’Riordan MN, Kiely M, Higgins JR, Cashman KD. Prevalence of suboptimal vitamin d status during pregnancy. Ir Med J. 2008; 101:240-3.

Holick M. Vitamin D deficiency. N Engl J Med. 2007; 357:266-81.

How to Cite
Martins, A., Bettencourt, A., & Torres, T. (2018). Effect of Month of Birth on the Risk of Developing Psoriasis. Journal of the Portuguese Society of Dermatology and Venereology, 75(4), 337-342. https://doi.org/10.29021/spdv.75.4.872
Original Articles