Infrastructure is the facilities which support modern human life, namely: water supply, sewage plants, housing, roads, cable networks, food supply facilities, schools, hospitals, airports, community meeting places, business and government buildings, bridges, railways.
Infrastructure is closely connected with standard of living and population. Every time the population doubles, it follows that the infrastructure must at least double, often more than that.
If a country is poor – and the highest population growth is in poor countries – then its government cannot provide the needed infrastructure. Standard of living drops, and this may lead to other evils.