The main goal of the Human Fertility Database (HFD) is to provide access to detailed high-quality data on cohort and period fertility to a broad audience of users. We seek to establish the HFD as a key resource for monitoring, analyzing, comparing, and forecasting fertility as well as for studying causes and consequences of fertility change in the industrialized world. The uniform format of HFD data facilitates comparative analysis across countries and regions and encourages researchers to move beyond the simple indicators such as the period Total Fertility Rates.
The HFD provides age-, cohort- and (whenever possible) birth-order-specific fertility rates, crude, cumulative and total fertility rates, tempo-adjusted total fertility rates, mean ages at birth, standard deviation in mean ages at birth, parity progression ratios, and also cohort and period fertility tables for national populations or areas. In addition, the HFD provides input data from which these measures and fertility tables are computed. The input data consist of detailed birth counts and estimates of female population exposure obtained from officially recognized sources.
The following features should make the HFD particularly attractive to its users:
For each population, one and the same set of methods is applied for the production of uniform output data. This facilitates comparability of the HFD data and indicators across countries and time.
The HFD is limited to populations where the registration of births by official statistical agencies is virtually complete and where population estimates over the range of reproductive ages are reliable. Methods employed in the HFD for obtaining output data do not include any treatment or adjustment of the input data for completeness and coverage.
Similarly to the Human Mortality Database (HMD), we are following four guiding principles: comparability, flexibility, accessibility, and reproducibility.
We provide complete documentation of all data available through this site as well as full descriptions of methods applied and specific features of country data sets. A complete description of the HFD methodology is given in the Methods Protocol. For each country, the description of data sources is given in the References document posted on the respective country page. General country-specific information (completeness, coverage, data quality issues, definitions, etc.) can be found in Background and Documentation files within each country section.
The HFD provides free access to the data. Before gaining full access to the database, you must become a registered user, which requires accepting our user agreement.
The HFD process for computing output fertility indicators from input data on births and population can be briefly described as a sequence of steps, which are specified below. In the process, the following data, indicators and outputs are produced:
Detailed descriptions of the HFD methodology are given in the Methods Protocol. The following items provide a concise overview of data processing and methodology.
The source data are collected from official and other validated sources, especially national statistical offices, statistical and demographic yearbooks, special tabulations from national registry data and official statistics websites. We are collecting relevant documents by data providers and also scientific literature explaining data collection routines, related regulations and practices and other factors affecting the quality of data on births and female population.
Special attention is paid to the following aspects of these 'raw' data:
The HFD aims at providing opportunities for comparative studies on fertility in different countries and/or time periods. In this regard, consistency across the whole data universe is an important priority. That is why we apply a uniform set of procedures to each population.
The desire for uniformity is hindered by the significant variability in the original data formats and the lack of sufficient detail in these 'raw' data. For example, the original birth data can be provided for one-year vs. five-year age groups, they may not always include cohort dimension, they may show broader or narrower ranges of available ages, they may include births with unknown birth order, or they may show total births instead of live births.
The HFD methodology includes procedures for the transformation of any set of raw data into data classified by single years of age ranging from age <=12 to 55+, by single-year birth cohorts, and (whenever possible) by birth orders varying from 1 to 5+. Births with unknown age of the mother are distributed proportionally across the range of known ages of the mother. Five-year age groups are additionally split into single-year ages by means of spline interpolation. For each age, births with unknown birth order are distributed proportionally across known birth orders. Birth orders higher than five are aggregated into birth order 5+. If needed, age-specific birth counts are extrapolated toward younger and older ages to cover the range of ages from 12 to 55 years. For each age, births are additionally split by year of birth of the mother (if such information is not present in input data).
At the same time, the data for each country are carefully checked and processed, with a view on their specificities, which are outlined in the country documentation file and, if needed, country experts are consulted. The data processing concerns checks for specific data problems and correction of errors, consultations with local demographers and statisticians, investigations of country documents and literature, comparisons with alternative fertility data and estimates. These procedures help to assure the high data quality standard for each HFD country.
In addition to the main data set, users are offered an “HFD lite” option, which includes Excel tables featuring the most commonly used aggregate fertility indicators for all HFD countries: total fertility rate, tempo-adjusted total fertility rate, mean age at birth, mean age at first birth, completed cohort fertility, and cohort parity distribution. These data are accessible without registration to all interested users.