"Maternal mortality" refers to obstetric deaths to women that occur during pregnancy, childbirth, or within 42 days of delivery or end of a pregnancy. The maternal mortality ratio is the number of maternal deaths per 100,000 live births.

In late 2015, The DHS Program began implementing changes to the maternal mortality questionnaires and terminology to clarify the distinction between maternal and pregnancy-related mortality. WHO defines maternal mortality as deaths to women while pregnant, during childbirth, or within 42 days of delivery or end of pregnancy that are due to the pregnancy. Deaths due to accidents or acts of violence that occur during this time period are not counted as maternal deaths. DHS defines pregnancy-related mortality as deaths to women from any cause while pregnant, during childbirth, or within 2 months of delivery or end of pregnancy. “Pregnancy-related” refers only to the timing of the death, and not to the cause of the death.

The DHS Program has collected information on pregnancy-related mortality since the late 1980s, so data users can examine trends in the pregnancy-related mortality ratio. However, DHS estimates of the pregnancy-related mortality ratio are not a precise measure of pregnancy-related mortality and their limitations can make interpretation difficult, particularly when trying to determine if the pregnancy-related mortality ratio has changed between surveys.