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Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study

OBJECTIVES: To evaluate the associations between birth month, birth season, and overall and cardiovascular disease mortality, and to examine the role of familial and socioeconomic factors in these associations. DESIGN: Prospective cohort study. SETTING: Nurses’ Health Study, established in 1976, an...

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Autores principales: Zhang, Yin, Devore, Elizabeth E, Strohmaier, Susanne, Grodstein, Francine, Schernhammer, Eva S
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BMJ Publishing Group Ltd. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7190053/
https://www.ncbi.nlm.nih.gov/pubmed/31852664
http://dx.doi.org/10.1136/bmj.l6058
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author Zhang, Yin
Devore, Elizabeth E
Strohmaier, Susanne
Grodstein, Francine
Schernhammer, Eva S
author_facet Zhang, Yin
Devore, Elizabeth E
Strohmaier, Susanne
Grodstein, Francine
Schernhammer, Eva S
author_sort Zhang, Yin
collection PubMed
description OBJECTIVES: To evaluate the associations between birth month, birth season, and overall and cardiovascular disease mortality, and to examine the role of familial and socioeconomic factors in these associations. DESIGN: Prospective cohort study. SETTING: Nurses’ Health Study, established in 1976, an ongoing prospective cohort study in the United States. PARTICIPANTS: Female registered nurses who reported information on date of birth at study enrolment (n=116 911, 1976-2014, followed for 38 years). EXPOSURE: Birth month and astronomical birth season (based on solstices and equinoxes as boundaries of the season categories). MAIN OUTCOME MEASURES: Age and various multivariable adjusted hazard ratios and 95% confidence intervals for the association between birth months (using November as the reference), astronomical birth season (using autumn as the reference), and overall and cardiovascular disease specific mortality were assessed using Cox proportional hazards models. RESULTS: Among study participants, 43 248 overall deaths were documented during 4 136 364 person years of follow-up since enrolment, including 8360 cardiovascular disease related deaths. In fully adjusted multivariable analyses, no significant association was observed between birth month, birth season, and overall mortality. Compared with women born in November, increased cardiovascular disease mortality was observed among those born from March to July (hazard ratio for March, 1.09, 95% confidence interval 0.98 to 1.21; April, 1.12, 1.00 to 1.24; May, 1.08, 0.98 to 1.20; June, 1.07, 0.96 to 1.19; and July 1.08, 0.98 to 1.20). Those born in April had the highest cardiovascular disease mortality, and those born in December had the lowest (December, 0.95, 0.85 to 1.06). The relative difference between the lowest and highest risk month was 17.89%. Women born in spring (1.10, 1.04 to 1.17) and summer (1.09, 1.03 to 1.16) had a higher cardiovascular disease mortality than women born in the autumn. Adjustment for familial and socioeconomic factors did not change these results. The relative difference between the lowest and highest risk season was 10.00%. CONCLUSION: Participants born in the spring and summer (especially those born in March-July) had a slight but significant increase in cardiovascular disease specific mortality. However, no seasonal birth month effect was observed among women for overall mortality. Familial and socioeconomic factors did not appear to alter these associations. Further studies are required to confirm these findings and reveal mechanisms of these seasonal birth month effects in cardiovascular disease mortality.
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spelling pubmed-71900532020-05-01 Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study Zhang, Yin Devore, Elizabeth E Strohmaier, Susanne Grodstein, Francine Schernhammer, Eva S BMJ Research OBJECTIVES: To evaluate the associations between birth month, birth season, and overall and cardiovascular disease mortality, and to examine the role of familial and socioeconomic factors in these associations. DESIGN: Prospective cohort study. SETTING: Nurses’ Health Study, established in 1976, an ongoing prospective cohort study in the United States. PARTICIPANTS: Female registered nurses who reported information on date of birth at study enrolment (n=116 911, 1976-2014, followed for 38 years). EXPOSURE: Birth month and astronomical birth season (based on solstices and equinoxes as boundaries of the season categories). MAIN OUTCOME MEASURES: Age and various multivariable adjusted hazard ratios and 95% confidence intervals for the association between birth months (using November as the reference), astronomical birth season (using autumn as the reference), and overall and cardiovascular disease specific mortality were assessed using Cox proportional hazards models. RESULTS: Among study participants, 43 248 overall deaths were documented during 4 136 364 person years of follow-up since enrolment, including 8360 cardiovascular disease related deaths. In fully adjusted multivariable analyses, no significant association was observed between birth month, birth season, and overall mortality. Compared with women born in November, increased cardiovascular disease mortality was observed among those born from March to July (hazard ratio for March, 1.09, 95% confidence interval 0.98 to 1.21; April, 1.12, 1.00 to 1.24; May, 1.08, 0.98 to 1.20; June, 1.07, 0.96 to 1.19; and July 1.08, 0.98 to 1.20). Those born in April had the highest cardiovascular disease mortality, and those born in December had the lowest (December, 0.95, 0.85 to 1.06). The relative difference between the lowest and highest risk month was 17.89%. Women born in spring (1.10, 1.04 to 1.17) and summer (1.09, 1.03 to 1.16) had a higher cardiovascular disease mortality than women born in the autumn. Adjustment for familial and socioeconomic factors did not change these results. The relative difference between the lowest and highest risk season was 10.00%. CONCLUSION: Participants born in the spring and summer (especially those born in March-July) had a slight but significant increase in cardiovascular disease specific mortality. However, no seasonal birth month effect was observed among women for overall mortality. Familial and socioeconomic factors did not appear to alter these associations. Further studies are required to confirm these findings and reveal mechanisms of these seasonal birth month effects in cardiovascular disease mortality. BMJ Publishing Group Ltd. 2019-12-18 /pmc/articles/PMC7190053/ /pubmed/31852664 http://dx.doi.org/10.1136/bmj.l6058 Text en Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
spellingShingle Research
Zhang, Yin
Devore, Elizabeth E
Strohmaier, Susanne
Grodstein, Francine
Schernhammer, Eva S
Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title_full Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title_fullStr Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title_full_unstemmed Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title_short Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study
title_sort birth month, birth season, and overall and cardiovascular disease mortality in us women: prospective cohort study
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7190053/
https://www.ncbi.nlm.nih.gov/pubmed/31852664
http://dx.doi.org/10.1136/bmj.l6058
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