1. Statistics Explainedhttps://ec.europa.eu/eurostat/statistics-explained/index.php?title=Fertility_statistics
2. International Institute for Sustainable Developmenthttps://sdg.iisd.org/news/2021-population-data-sheet-highlights-declining-fertility-rates/
3. New World Bank Country Classifications by Income Level: 2021–2022https://blogs.worldbank.org/opendata/new-world-bank-country-classifications-income-level-2021-2022
4. Crude Birth Rate (Annual Number of Live Births per 1000 Population)https://www.who.int/data/maternal-newborn-child-adolescent-ageing/indicator-explorer-new/mca/crude-birth-rate-(births-per-1000-population)
5. Mean Body Mass Index Trends among Adults, Age-Standardized (kg/m²) Estimates by Countryhttps://apps.who.int/gho/data/node.main.A904?lang=en