<p>The literature shows that in-utero maternal stress significantly reduces newborn birth weight. If so, it is plausible that women may avoid becoming pregnant during periods of heightened stress. We tested this hypothesis in the context of a home baseball team’s championship victory—a time when people are likely to gather and make noise, potentially affecting emotional states and stress. Our analysis uses data from South Korea, where baseball is the most popular professional sport. Because the championship team’s region varied from year to year, we employed a difference-in-differences estimation strategy. We found that a home team’s championship win had no effect on the overall birth rate nine months later. However, among women with college degrees, the birth rate declined by 4.7%, while the birth rate among women without college degrees remained unchanged.</p>