Final answer:
Newborn infants in developed countries are expected to live about 79 years on average. Infant mortality rates and life expectancy are influenced by healthcare, socioeconomic status, and the standard of living. Over time, life expectancy has risen globally, with distinctions being made between developed and developing countries.
Step-by-step explanation:
The expected lifespan of a newborn infant can greatly depend on their country of origin due to differences in infant mortality rates and life expectancy. In developed countries, a newborn male or female infant could expect to live about 79 years, as seen in countries like the United States, Australia, and other more affluent nations. Factors such as healthcare, standard of living, and socio-economic status significantly affect the life expectancy, with wealthier nations often experiencing higher life expectancies and lower infant mortality rates.
Life expectancy has increased considerably from historical numbers of around 20 to 30 years at birth, with the global average in 2013 being approximately 67 years, and even higher in developed countries. However, life expectancy can vary based on gender, with numbers from 2015 indicating an average of 77 years for males and 82 years for females in the United States.
Infancy, which refers to the first year of life, is a period of rapid growth where a healthy, well-nourished infant typically triples their birth weight and doubles their birth length by their first birthday. Overall, the expected lifespan of a newborn today is influenced by a multitude of factors, but particularly by the level of socio-economic development and healthcare quality in their country.