maternal death

A maternal death is not simply a woman who dies while pregnant. The World Health Organization defines it narrowly, and the narrowness is what makes the number comparable between countries. It counts a female death from any cause related to or aggravated by pregnancy or its management, occurring during pregnancy and childbirth or within 42 days of the pregnancy ending. Deaths from accidental or incidental causes are excluded, so a pregnant woman killed in a road crash is not a maternal death.

Two parts of that definition do most of the work. The 42 day window catches the deaths that follow a birth rather than accompany it, which is when severe bleeding and infection most often kill. The phrase related to or aggravated by pregnancy catches conditions a woman already had, such as heart disease or anaemia, which pregnancy can turn fatal.

Counting maternal deaths this way is what allows the maternal mortality ratio to be built from them, and what lets one country's figure be set beside another's. Where civil registration is incomplete, the counts are modelled from surveys and censuses rather than tallied directly, which is why national figures are usually published as estimates with a range around them.