Due to poor medicine and nutrition most likely
Enqelāb-e Iran; also known as the Islamic Revolution or the 1979 Revolution)refers to events involving the overthrow of the Pahlavi dynastyunder Mohammad Reza Shah Pahlavi, who was supported by the United States,[9] and eventual replacement of 2,500 years of continuous Persian monarchywith an Islamic Republic under the Grand AyatollahRuhollah Khomeini, the leader of the revolution, supported by a wide range of people including various Islamist and leftist organizations[10] and student movements.
I dont really know that much about history but i will try my best to
help you
