I use variation in early-life exposure to the Cotton Famine, an exogenous shock to health and income in Britain occasioned by the embargo on Southern cotton during the American Civil War, as a natural experiment to explain variation in fertility and mortality in 19th Century Britain. I find that the Cotton Famine acted primarily as an adverse income shock, resulting in a roughly 8% reduction in cohort size among exposed cohorts up to age 19. After this point in the life-course, cohort size rises, suggesting a selection effect wherein deaths that would have occurred in later age bands occurred sooner due to poor health in childhood. Poor maternal health due to increased workplace hazards appears to have played an insignificant role in cohort size reduction, either because mill closures removed expectant mothers from these health hazards, or because these hazards were not extreme enough to affect fetal health. It is worth noting, however, that the Cotton Famine had heterogeneous treatment effects: where cotton made up a larger share of women’s employment, the size of exposed cohorts is larger. This suggests a substitution effect through which female unemployment due to mill closures resulted in better infant care, characterized by decreases in infant mortality and/or increases in fertility. This finding is consistent with present-day studies on the public health effects of recessions, and is supported by results on mortality by cause. Lastly, I find that Poor Law relief was unable to ameliorate the adverse effects of the event’s shocks to income.