According to the World Health Organization (WHO), "A maternal death is defined as the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes."

Generally, there is a distinction between a direct maternal death that is the result of a complication of the pregnancy, delivery, or management of the two, and an indirect maternal death that is a pregnancy-related death in a patient with a preexisting or newly developed health problem unrelated to pregnancy. Fatalities during but unrelated to a pregnancy are termed accidental, incidental, or nonobstetrical maternal deaths.

The U.S. Joint Commission on Accreditation of Healthcare Organizations calls maternal mortality is a "sentinel event", and uses it to assess the quality of a health care system.

However, a number of issues need to be recognized. First of all, the WHO definition is only one of many; other definitions may also include accidental and incidental causes. Cases with "incidental causes" include deaths secondary to violence against women that may be related to the pregnancy and be affected by the socioeconomic and cultural environment. Also, it has been reported that about 10% of maternal deaths may occur late, that is after 42 days after a termination or delivery, thus, some definitions extend the time period of observation to one year after the end of the gestation.