Utah study links dying young to large families
The study, which will be published in the January issue of The Proceedings of the National Academy of Science, shows both women and men have a higher chance of dying young if they have larger families. That risk is especially high for women, who drastically increase their chance of dying earlier when they have had more than four children, the study states.
The study, led by U. professor Ken Smith, analyzed data from nearly 22,000 couples from the Utah Population Database who were married between 1860 and 1895. While childbirth has changed since then, Smith said the toll on female bodies by producing large numbers of children still exists today. Perhaps more surprising, he added, men also showed an increased mortality rate corresponding to the number of children they fathered, although it is much less than the impact on women.
"These kinds of fertility patterns and survival patterns are still present today in developing countries. It's not like these stresses and costs associated with having children have disappeared from the planet because it's the 21st century," said Smith, a professor of family and consumer studies at the U.
Those patterns were similar for men, although much less drastic, dipping from a 99.5 percent survival rate for men with one to three children to a 97.5 rate for men with more than 12 children.
While modern medical advances may mitigate some of the risks of death following childbirth, Smith said that same progress has allowed women to continue having children into their late 30s and 40s. Those women have a much higher risk of dying within a year after their last child is born, he said.
Smith added, however, that the study is not an attempt to peg the number of children as the direct cause of shorter lifespans among women. Women who have more children may be more likely to die after their last is born simply because they are older by the time they are finished bearing children, for example.
But Smith added the fact that women with more children are more likely than men to die within a year of their last birth does hint at the relationship between increased reproduction and mortality.
"Our results are consistent with the idea that reproduction requires a trade-off between quality and quantity, and may help explain the evolution of menopause as a means of increasing mother survival," he said.
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