Demographic historians have long suspected that cultural factors played an important role in the early decline of fertility in nineteenth-century America. Using the recently released 1850 and 1880 IPUMS samples, this article investigates correlates of marital fertility among native-born white women of native parentage, focusing on the relationship between religion and fertility. Two proxies of religious sentiment are found to be significantly correlated with marital fertility. First, county-level census data indicate that the presence of Congregationalists and Universalists was associated with lower marital fertility, while the presence of Lutherans was associated with higher marital fertility. Second, the proportion of own children with biblical names - believed to be a proxy of parental religiosity - is found to be positively associated with marital fertility. These results are consistent with the hypothesis that traditional religious beliefs were an impediment to the adoption of family limitation strategies.