Fertility rates refer to the average number of children born to a woman over her lifetime. This measure helps demographers understand population growth and decline. A high fertility rate often indicates a younger population and can be associated with developing countries, while a low fertility rate may suggest an aging population and is commonly seen in developed nations. Fertility rates can be influenced by various factors, including cultural norms, economic conditions, and access to healthcare. Changes in these factors can lead to shifts in fertility rates, impacting overall population dynamics and social structures within a country.