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.

中文翻译：

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美国妇女的出生月份，出生季节以及整体和心血管疾病的死亡率：前瞻性队列研究。

目的评估出生月份，出生季节与总体和心血管疾病死亡率之间的关联，并检查家族和社会经济因素在这些关联中的作用。设计前瞻性队列研究。设置护士健康研究，成立于1976年，是美国一项正在进行的前瞻性队列研究。参与者女性注册护士在研究入组时报告出生日期的信息（n = 116 911，1976-2014年，其后38年）。暴露出生月份和天文出生季节（基于至年和昼夜平分点作为季节类别的边界）。主要观察指标出生月份之间的年龄和各种经多变量调整的危险比以及95％的置信区间（以11月为参考），使用Cox比例风险模型评估天文出生季节（以秋季为参考），以及总体和心血管疾病的特定死亡率。结果在研究参与者中，自入选以来的4 136 364人年的随访期间，共记录了43248例死亡，包括8360例与心血管疾病相关的死亡。在完全调整的多变量分析中，未发现出生月份，出生季节和总死亡率之间有显着相关性。与11月出生的妇女相比，3月至7月出生的妇女的心血管疾病死亡率增加（3月的危险比为1.09，95％置信区间为0.98至1.21； 4月为1.12，1.00至1.24； 5月为1.08，0.98至0.98 1.20； 6月，1.07，0.96至1.19；以及7月1.08，0.98至1.20）。4月出生的人的心血管疾病死亡率最高，而12月出生的人的心血管疾病死亡率最低（12月的0.95、0.85至1.06）。最低和最高风险月份之间的相对差异为17.89％。春季（1.10，1.04至1.17）和夏季（1.09，1.03至1.16）出生的妇女比秋季出生的妇女有更高的心血管疾病死亡率。调整家庭和社会经济因素并没有改变这些结果。最低和最高风险季节之间的相对差异为10.00％。结论春季和夏季出生的参与者（尤其是三月至七月出生的参与者）的心血管疾病特异性死亡率略有增加，但显着增加。但是，没有观察到妇女在总死亡率方面的季节性出生月份影响。家庭和社会经济因素似乎并未改变这些关联。需要进一步的研究来证实这些发现，并揭示这些季节性出生月份影响心血管疾病死亡率的机制。