lifetime risk of maternal death

Lifetime risk of maternal death answers a different question from the maternal mortality ratio. The ratio measures how dangerous one birth is. The lifetime risk measures how dangerous a whole reproductive life is, and the World Health Organization states it as the probability that a 15-year-old woman will eventually die from a maternal cause. It is normally written as odds, one in so many 15-year-olds, which is why the two figures for the same country never look alike.

Two things drive it. The first is how likely a woman is to die at each birth, which is what the ratio measures. The second is how many births she is likely to have, so where families are larger the same risk per birth accumulates into a higher risk across a life. The inter-agency group that produces the estimates, made up of WHO, UNICEF, UNFPA and the World Bank, calculates the figure on the assumption that current levels of fertility and mortality do not change, and it allows for competing causes of death, meaning the chance that a woman dies of something else first.

The gap between countries is wide. WHO puts the lifetime risk at about one in 66 for a 15-year-old in a low income country and about one in 7,933 in a high income country. The figure is easy to misread as the danger of a single pregnancy, and it is not that. It is the risk accumulated over a whole reproductive life, and it falls both when giving birth becomes safer and when women have fewer births.