Introduction The etiology of congenital diaphragmatic hernia (CDH) remains unknown and only 10 to 30% of patients have a genetic cause. Seasonal variation is known to contribute to the development of some congenital anomalies. Our aim was to investigate whether CDH births have seasonal variation.

Materials and Methods A literature review was conducted for CDH and seasonality. Moreover, data from the CDH International Patient Registry Database were collected for infants with due dates between 2008 and 2014. Due dates were used to determine seasonal distribution of births. Birth rates per month in the United States and Canada were extracted from publicly available databases. Data were analyzed using analysis of variance and contingency tables.

Results First, the literature review revealed 11 articles, of which 3 were eligible for inclusion. These studies reported conflicting results on seasonality of CDH. Second, we extracted due dates from the CDH International Patient Registry Database (1,259 patients) and found that there were fewer due dates in winter months (12.1 ± 4 patients/month) than in summer (16.7 ± 6 patients/month; p = 0.011) and fall months (16.3 ± 5 patients/month; p = 0.022). Although this trend was similar to that of all births in the United States and Canada, a lower incidence was observed in winter for CDH infants (20.2%) than for the general population (24.1%, p = 0.0012). CDH survival rate did not vary by season.

Conclusion This study provides evidence for a seasonal variation of CDH births. No causative link was established between CDH development and seasonality. Population-based studies with a focus on exposome data are needed to explain seasonal variation in CDH.

简介 先天性膈疝 (CDH) 的病因仍然未知，只有 10% 到 30% 的患者有遗传原因。众所周知，季节性变化会导致某些先天性异常的发生。我们的目的是调查 CDH 出生是否有季节性变化。

材料和方法 对 CDH 和季节性进行了文献综述。此外，还从 CDH 国际患者登记数据库中收集了预产期在 2008 年至 2014 年之间的婴儿的数据。预产期用于确定出生的季节性分布。美国和加拿大每月的出生率是从公开可用的数据库中提取的。使用方差分析和列联表分析数据。

结果 首先，文献复习发现11篇文章，其中3篇符合纳入条件。这些研究报告了 CDH 季节性的相互矛盾的结果。其次，我们从 CDH 国际患者登记数据库（1,259 名患者）中提取截止日期，发现冬季月份（12.1 ± 4 名患者/月）的截止日期少于夏季（16.7 ± 6 名患者/月；p  = 0.011 ） ) 和秋季月份（16.3 ± 5 名患者/月；p  = 0.022）。尽管这一趋势与美国和加拿大所有新生儿的趋势相似，但在冬季观察到 CDH 婴儿 (20.2%) 的发病率低于一般人群 (24.1%，p  = 0.0012)。CDH存活率不随季节变化。

结论 本研究为 CDH 出生的季节性变化提供了证据。CDH 发展和季节性之间没有建立因果关系。需要以暴露组数据为重点的基于人群的研究来解释 CDH 的季节性变化。