Abstract：
OBJECTIVE: The length of newborns shows seasonal fluctuations, but the patterns of these fluctuations vary greatly. This study analyses the fluctuation in birth length by birth month and temporal changes in Austrian newborns from the 1984 to 2021 birth cohorts.
METHODS: A total of 2 317 927 singleton-term births between 1984 and 2021 in Austria were included in this retrospective population-based cohort study. A strict inclusion criterion was the Austrian citizenship of the mother. The effect of month of birth (MOB) on birth length was estimated using a multivariable linear model adjusting for maternal educational level, newborn sex, gestational age, year of birth (YOB) of the newborn, and parity of the mother.
RESULTS: Newborn length varied by MOB, but there was also a temporal trend. In the birth cohorts up to 2004, the longest newborns were born in February, while from 2008 onward, the longest birth lengths were observed in the summer months.
CONCLUSIONS: In this Austrian population-based sample, birth length shows nonrandom fluctuations by birth month. These patterns, however, varied considerably over time.
METHODS: A total of 2 317 927 singleton-term births between 1984 and 2021 in Austria were included in this retrospective population-based cohort study. A strict inclusion criterion was the Austrian citizenship of the mother. The effect of month of birth (MOB) on birth length was estimated using a multivariable linear model adjusting for maternal educational level, newborn sex, gestational age, year of birth (YOB) of the newborn, and parity of the mother.
RESULTS: Newborn length varied by MOB, but there was also a temporal trend. In the birth cohorts up to 2004, the longest newborns were born in February, while from 2008 onward, the longest birth lengths were observed in the summer months.
CONCLUSIONS: In this Austrian population-based sample, birth length shows nonrandom fluctuations by birth month. These patterns, however, varied considerably over time.
摘要：
目的：新生儿的长度呈现季节性波动，但是这些波动的模式差异很大。这项研究分析了1984年至2021年奥地利新生儿出生队列中出生月份的出生长度波动和时间变化。
方法：这项以人口为基础的回顾性队列研究包括奥地利1984年至2021年期间的2317927例单足月新生儿。严格的纳入标准是母亲的奥地利国籍。出生月（MOB）对出生长度的影响是使用多变量线性模型对母亲的教育水平进行调整来估计的。新生儿性别,胎龄,新生儿的出生年份（YOB），和母亲的平等。
结果：新生儿身长因MOB而异，但也有一个时间趋势。在截至2004年的出生队列中，最长的新生儿出生在2月，而从2008年起,最长的出生长度在夏季。
结论：在这个以奥地利人口为基础的样本中，出生长度显示出生月份的非随机波动。这些模式，然而,随着时间的推移变化很大。
方法：这项以人口为基础的回顾性队列研究包括奥地利1984年至2021年期间的2317927例单足月新生儿。严格的纳入标准是母亲的奥地利国籍。出生月（MOB）对出生长度的影响是使用多变量线性模型对母亲的教育水平进行调整来估计的。新生儿性别,胎龄,新生儿的出生年份（YOB），和母亲的平等。
结果：新生儿身长因MOB而异，但也有一个时间趋势。在截至2004年的出生队列中，最长的新生儿出生在2月，而从2008年起,最长的出生长度在夏季。
结论：在这个以奥地利人口为基础的样本中，出生长度显示出生月份的非随机波动。这些模式，然而,随着时间的推移变化很大。
