BACKGROUND Despite persistent concerns about only children's disadvantage relative to individuals with siblings, existing health-related evidence is inconsistent. Recent evidence from Nordic countries about only children having poorer health outcomes may not apply elsewhere because selection processes differ across contexts. We investigate the midlife health of only children in the UK where one-child families tend to be socio-economically advantaged relative to large families. METHODS Using the 1946, 1958 and 1970 British birth cohort studies, we examine various biomarkers and self-reported measures of chronic disease by sibship size when respondents are aged in their mid-40s, mid-50s and mid-60s. We estimate separate linear probability models for each cohort, age and outcome, adjusting for childhood and early adulthood circumstances. RESULTS We found no evidence of only children differing from those with one, two or three or more siblings, at any age, in any of the cohorts, on: heart problems, hypertension, high triglycerides, high glycated haemoglobin or high C-reactive protein. However, compared with only children, the probability for cancer (0.019, 95% confidence interval [CI]: 0.002, 0.035; age 46/1970) and poor general health (0.060, CI: 0.015, 0.127; age 55/1958; and 0.110, CI: 0.052, 0.168; age 63/1946) was higher among those with three or more siblings. CONCLUSIONS There is no consistent pattern of only child health disadvantage for midlife chronic disease outcomes across ages or cohorts in the UK. Research should focus on better understanding how sibship size differentials are contingent on context.

中文翻译：

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独生子女的中年健康：三个具有全国代表性的英国队列中按同胞大小划分的慢性疾病指标和生物标志物。


背景尽管人们一直担心独生子女相对于有兄弟姐妹的个体处于不利地位，但现有的健康相关证据并不一致。北欧国家最近关于独生子女健康状况较差的证据可能不适用于其他地方，因为选择过程因环境而异。我们调查了英国独生子女的中年健康状况，其中独生子女家庭相对于大家庭往往具有社会经济优势。方法 使用 1946 年、1958 年和 1970 年英国出生队列研究，我们检查了受访者年龄在 40 多岁、50 多岁和 60 多岁之间时，按同胞大小划分的各种生物标志物和自我报告的慢性病指标。我们估计每个队列、年龄和结果的单独线性概率模型，并根据儿童期和成年早期的情况进行调整。结果 我们没有发现任何证据表明，在任何年龄、任何队列中，独生子女与有一个、两个或三个或更多兄弟姐妹的独生子女在以下方面存在差异：心脏问题、高血压、高甘油三酯、高糖化血红蛋白或高 C 反应蛋白。然而，与独生子女相比，患癌症的概率（0.019，95%置信区间[CI]：0.002，0.035；年龄46/1970）和总体健康状况不佳（0.060，CI：0.015，0.127；年龄55/1958；和0.110，CI：0.052，0.168；63/1946 岁）在有三个或更多兄弟姐妹的人中更高。结论 在英国，对于中年慢性病结果而言，仅儿童健康不利的情况并没有一致的模式。研究应侧重于更好地理解同胞关系规模差异如何取决于背景。