The intensive care unit (ICU) pregnant patient presents a number of difficulties.Basic principles of maternal and foetal physiology must be understood by doctors and nurses. The doctors must treat the mother while taking into account any negative consequences that diagnostic and therapeutic procedures might have on the foetus. This article largely focuses on the typical pregnant state, with relevant allusions to how pregnancy may impact the patient in situations related to the intensive care unit. ICU doctors should be knowledgeable with how the major organs adjust physiologically to the pregnant state.