Background: To date, historical fertility change in Mongolia has been analyzed starting from the 1960s. It is generally accepted that the adoption of pro-natalist policies resulted in very high fertility levels during the 1960s and 1970s and that their relaxation in the mid-1970s contributed to the onset of fertility decline.

Objective: The objective of this paper is to reconstruct fertility levels and trends in Mongolia before the 1960s in order to offer an alternative view of the historical fertility change in the country.

Methods: Mobilizing a large set of data from different sources and applying diverse estimation techniques, a consistent reconstruction of nearly a century of fertility change in Mongolia is conducted. For the first time, fertility estimates before 1960 are introduced. The quality of these estimates is assessed through cross-comparison and prospective reconstruction of the country’s population.

Results: The different fertility estimates give a very consistent picture of historical fertility change in Mongolia, indicating that total fertility stagnated until the late 1940s and then increased by about 2.5 children per woman within 15 years. The population of Mongolia can be consistently reproduced assuming almost constant fertility between 1918 and 1956.

Conclusions: The improvement in health and living standards related to the establishment of a socialist society is the main factor explaining the variations in fertility before the 1960s in Mongolia. This study reinstates the importance of social and economic development in explaining fertility change in the country.

Comments: This study calls for demographers to reconstruct long-term population development in statistically less-developed countries to better understand the global process of fertility transition.