Margaret Sanger established the first birth control clinic in New York in 1916. From the mid-1920s, "Sanger clinics" spread over the entire U.S. Combining newly digitized data on the roll-out of these clinics, full-count Census data, and administrative vital statistics, we find that birth control clinics accounted for 5.0–7.8% of the overall fertility decline until 1940. Moreover, birth control clinics had a significant and meaningful negative effect on the incidence of stillbirths and infant mortality. The effect of birth control clinics on puerperal deaths is consistently negative, yet insignificant. Further suggestive evidence points towards positive effects on female employment.