A large body of research has shown that children born after especially short or long birth intervals experience an elevated risk of poor perinatal outcomes, but recent work suggests this may be explained by confounding by unobserved family characteristics. We use Swedish population data on cohorts born 1981–2010 and sibling fixed effects to examine whether the length of the birth interval preceding the index child influences the risk of preterm birth, low birth weight, and hospitalization during childhood. We also present analyses stratified by salient social characteristics, such as maternal educational level and maternal country of birth. We find few effects of birth intervals on our outcomes, except for very short intervals (less than seven months) and very long intervals (>60 months). We find few differences in the patterns by maternal educational level or maternal country of origin after stratifying by the mother’s highest educational attainment.

中文翻译：

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瑞典的怀孕间隔和围产期和儿童健康：家庭内部和社会群体之间的比较。

大量研究表明，在特别短或长的生育间隔之后出生的儿童围产期结果不佳的风险升高，但最近的工作表明，这可能是由于未观察到的家庭特征造成的混淆。我们使用瑞典 1981-2010 年出生队列的人口数据和兄弟姐妹固定效应来检查索引孩子之前的出生间隔长度是否影响早产、低出生体重和儿童期住院的风险。我们还提供了按显着社会特征分层的分析，例如母亲的教育水平和母亲的出生国家。我们发现生育间隔对我们的结果几乎没有影响，除了非常短的间隔（少于 7 个月）和非常长的间隔（> 60 个月）。