Final answer:
World War II had a significant impact on population pyramids and birth rates, leading to the 'baby boom' phenomenon and subsequent changes in birth rates. These changes can be observed in population pyramids and are influenced by various factors.
Step-by-step explanation:
The impact of World War II on population pyramids and birth rates can be seen in the phenomenon known as the "baby boom." After the war, there was a significant increase in birthrates that lasted from 1945 until 1967. This can be observed in the population pyramid as a slight bulge in the age group of 48-70. As the population aged, this group was pushed upwards, creating a distinct shape in the pyramid.
During the war, there were also changes in birth rates. Many countries experienced a decline in births from 1975 to 1990, which can be attributed to the war's impact on the economy and social structure. However, there was another slight increase in birth rates from 1995 to 2000, indicating a complex interplay of factors.