Department of Public Health Sciences, School of Medicine, University of California, Davis, CA 95616, USA.
Epidemiology. 2011 Jul;22(4):469-75. doi: 10.1097/EDE.0b013e31821d0b53.
Studies of season of birth or season of conception can provide clues about etiology. We investigated whether certain months or seasons of conception are associated with increased risk of autism spectrum disorders, for which etiology is particularly obscure.
The study population comprises 6,604,975 children born from 1990 to 2002 in California. Autism cases (n = 19,238) were identified from 1990 through 2008 in databases of the California Department of Developmental Services, which coordinates services for people with developmental disorders. The outcome in this analysis was autism diagnosed before the child's sixth birth date. The main independent variables were month of conception and season of conception (winter, spring, summer, and fall). Multivariate logistic regression models were used to estimate odds ratios (ORs) with their 95% confidence intervals (CIs) for autism by month of conception.
Children conceived in December (OR = 1.09 [95% CI = 1.02-1.17]), January (1.08 [1.00-1.17]), February (1.12 [1.04-1.20]), or March (1.16 [1.08-1.24]) had higher risk of developing autism compared with those conceived in July. Conception in the winter season (December, January, and February) was associated with a 6% (OR = 1.06, 95% CI = 1.02-1.10) increased risk compared with summer.
Higher risks for autism among those conceived in winter months suggest the presence of environmental causes of autism that vary by season.
对出生季节或受孕季节的研究可以为病因学提供线索。我们研究了受孕的某些月份或季节是否与自闭症谱系障碍的风险增加有关，而自闭症谱系障碍的病因特别不明确。
研究人群包括 1990 年至 2002 年在加利福尼亚出生的 6604975 名儿童。1990 年至 2008 年期间，从加利福尼亚州发育服务部的数据库中确定了自闭症病例（n=19238），该数据库协调为发育障碍者提供服务。本分析中的结果是在儿童第六个出生日期之前诊断出的自闭症。主要的独立变量是受孕月份和受孕季节（冬季、春季、夏季和秋季）。使用多变量逻辑回归模型，根据受孕月份，估算自闭症的优势比（OR）及其 95%置信区间（CI）。
与 7 月受孕相比，12 月（OR=1.09[95%CI=1.02-1.17]）、1 月（1.08[1.00-1.17]）、2 月（1.12[1.04-1.20]）或 3 月（1.16[1.08-1.24]）受孕的儿童患自闭症的风险更高。与夏季相比，冬季（12 月、1 月和 2 月）受孕与自闭症风险增加 6%相关（OR=1.06，95%CI=1.02-1.10）。
在冬季受孕的自闭症风险较高表明存在自闭症的环境原因，且其原因因季节而异。
