Season of Birth and Later Outcomes: Old Questions, New Answers
研究发现出生季节与后期结果相关，但原因不明。本文提出新解释：母亲特征随季节变化，冬季出生者更多来自青少年或未婚母亲，家庭背景可解释近一半关联。
Season of birth is associated with later outcomes; what drives this association remains unclear. We consider a new explanation: variation in maternal characteristics. We document large changes in maternal characteristics for births throughout the year; winter births are disproportionally realized by teenagers and the unmarried. Family background controls explain nearly half of season-of-birth's relation to adult outcomes. Seasonality in maternal characteristics is driven by women trying to conceive; we find no seasonality among unwanted births. Prior seasonality-in-fertility research focuses on conditions at conception; here expected conditions at birth drive variation in maternal characteristics while conditions at conception are unimportant.