Gun violence is ubiquitous across the United States, with gun-related deaths reaching an all-time high in 2021. The prevalence of gunfire results in loud and potentially stress-inducing sounds, which may adversely affect critical stages of in-utero development. However, gunfire is largely unreported, creating a unique challenge for researchers to understand its consequences. In this paper, we mitigate this shortcoming by leveraging data from ShotSpotter—an acoustic gunshot technology which uses an array of sensors placed on city structures to detect the sound of gunfire. We combine this unique data source with the universe of births in a large California city over a four-year period (2016-2020), each matched to a mother’s residence. Using the variation in gunfire detections from ShotSpotter at the census-block level, we employ a difference-in-differences methodology and find that gunshot noise creates substantial decreases in gestation lengths, resulting in an increase in preterm deliveries. These effects are driven entirely by times of the day when civilians are awake, and are particularly concentrated among mothers with low levels of education. These results suggest that gunshot noise is a major factor contributing to the income inequities in pregnancy outcomes.