Infant mortality, a reflection of socioeconomic and health conditions of a population, is shaped by diverse factors. This study delves into a pre-industrial population, scrutinizing neonatal and post-neonatal deaths separately. Family factors such as mortality crises, religion, and legitimacy are also explored. Data of 9,086 people obtained through multigenerational information from ecclesiastic records from 1603 to 1908 were analysed by means of a joinpoint regression analysis. Death risk was assessed with univariate and multivariate Cox Proportional Hazard models. Early neonatal mortality was 5.6% of births and showed a gradual and steady increase from 1630 to 1908, with no substantial improvement over the three centuries analysed. Late neonatal (4.3% of births) and post-neonatal mortality (18.7% of births) shared a different pattern, showing a decline between the mid-18th and mid-19th centuries, and an increase by the 20th century that could be caused by socioeconomic factors and the impact of several epidemics. In the historical population of Hallstatt, infant survival was influenced by the sex of the newborn, the death of the mother and the precedent sibling, and by the birth interval. Environmental and cultural factors, such as mortality crises and religion, influenced late neonatal and post-neonatal mortality, but not early neonatal mortality. The results highlight the need to independently assess early neonatal mortality in studies of infant mortality in historical populations, and to use as complete time periods as possible to capture differences in mortality patterns.