Objective To investigate the association between gestational age at birth and cognitive outcomes in adolescence. Design Nationwide population based full sibling cohort study. Setting Denmark. Participants 1.2 million children born between 1 January 1986 and 31 December 2003, of whom 792 724 had one or more full siblings born in the same period. Main outcome measures Scores in written language (Danish) and mathematics examinations as graded by masked assessors at the end of compulsory schooling (ninth grade, ages 15-16 years), in addition to intelligence test score at military conscription (predominantly at age 18 years) for a nested sub-cohort of male adolescents. School grades were standardised as z scores according to year of examination, and intelligence test scores were standardised as z scores according to year of birth. Results Among 792 724 full siblings in the cohort, 44 322 (5.6%) were born before 37+0 weeks of gestation. After adjusting for multiple confounders (sex, birth weight, malformations, parental age at birth, parental educational level, and number of older siblings) and shared family factors between siblings, only children born at <34 gestational weeks showed reduced mean grades in written language (z score difference −0.10 (95% confidence interval −0.20 to −0.01) for ≤27 gestational weeks) and mathematics (−0.05 (−0.08 to −0.01) for 32-33 gestational weeks, −0.13 (−0.17 to −0.09) for 28-31 gestational weeks, and −0.23 (−0.32 to −0.15) for ≤27 gestational weeks), compared with children born at 40 gestational weeks. In a nested sub-cohort of full brothers with intelligence test scores, those born at 32-33, 28-31, and ≤27 gestational weeks showed a reduction in IQ points of 2.4 (95% confidence interval 1.1 to 3.6), 3.8 (2.3 to 5.3), and 4.2 (0.8 to 7.5), respectively, whereas children born at 34-39 gestational weeks showed a reduction in intelligence of <1 IQ point, compared with children born at 40 gestational weeks. Conclusions Cognitive outcomes in adolescence did not differ between those born at 34-39 gestational weeks and those born at 40 gestational weeks, whereas those with a gestational age of <34 weeks showed substantial deficits in multiple cognitive domains. Data can be obtained by submitting a research protocol to the Danish Data Protection Agency and by applying to the Ministry of Health’s Research Service, Statistics Denmark, and the Danish Ministry of Defence, respectively. The data do not belong to the authors, and they are not permitted to share data, except in aggregate form.

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出生时的胎龄和青春期的认知结果：基于人群的完整同胞队列研究

目的 探讨出生胎龄与青春期认知结果之间的关系。设计基于全国人群的全同胞队列研究。设置丹麦。参与者 1986 年 1 月 1 日至 2003 年 12 月 31 日期间出生的 120 万儿童，其中 792 724 人有一个或多个同胞兄弟姐妹在同一时期出生。主要成果指标 书面语言（丹麦语）和数学考试分数，由蒙面评估员在义务教育结束时（九年级，年龄 15-16 岁）评分，此外还有征兵时的智力测试分数（主要在 18 岁时） ) 对于嵌套的男性青少年子队列。学校成绩根据考试年份标准化为 z 分数，智力测验分数根据出生年份标准化为 z 分数。结果 在该队列的 792 724 名同胞兄弟姐妹中，44 322 名 (5.6%) 在妊娠 37+0 周前出生。在调整了多个混杂因素（性别、出生体重、畸形、父母出生年龄、父母教育水平和兄弟姐妹的数量）和兄弟姐妹之间的共同家庭因素后，只有小于 34 孕周出生的孩子的书面语言平均成绩下降（≤27 孕周的 z 得分差异 -0.10（95% 置信区间 -0.20 至 -0.01））和数学（32-33 孕周 -0.05（-0.08 至 -0.01），-0.13（-0.17 至 -0.09 ) 28-31 孕周，-0.23（-0.32 至-0.15）≤27 孕周），与 40 孕周出生的儿童相比。在具有智力测试分数的同胞嵌套子队列中，出生在 32-33、28-31、和 ≤27 孕周显示 IQ 点分别降低 2.4（95% 置信区间 1.1 至 3.6）、3.8（2.3 至 5.3）和 4.2（0.8 至 7.5），而 34-39 孕周出生的儿童显示与妊娠 40 周出生的儿童相比，智力下降 <1 IQ 点。结论 妊娠 34-39 周出生的人和妊娠 40 周出生的人在青春期的认知结果没有差异，而胎龄 <34 周的人在多个认知领域表现出显着缺陷。可以通过向丹麦数据保护局提交研究协议并分别向卫生部研究服务部、丹麦统计局和丹麦国防部申请获得数据。数据不属于作者，