Final answer:
The Fertility Rate is defined as the average number of children a woman is expected to give birth to during her lifetime.
Step-by-step explanation:
The concept defined as the average number of children born per woman during her lifetime is the Fertility Rate. This rate takes into account the number of live births women are expected to have over their lifetimes, giving demographers and sociologists critical information to understand population growth and patterns. Aspects like infant mortality and emigration can influence fertility rates, and varying rates can be seen across different regions and countries. For example, a significant decline in fertility rates has been observed in countries affected by climate change, violence, and emigration. Moreover, the fertility rate plays a vital role in determining whether a country's population is increasing or decreasing in relation to the replacement level of 2.1 children per woman.