Study: Birth Control Access May Not Cut Fertility

October 17, 2012 • Family Planning, News

The following story was published last week on, a website exclusively focused on the latest discoveries by scientists at top research universities in the US, UK, Canada, and Australia. It reports on efforts at the University of Santa Barbara to develop and test a conceptual model of factors influencing women’s ideal family size (IFS) in a natural fertility population, the Tsimane of Bolivia.

For Tsimane, birth control access may not cut fertility


UC SANTA BARBARA (US) – For an indigenous group who live in the lowlands of Bolivia’s Amazon basin, access to contraception and education doesn’t necessarily lead to lower fertility, a new study suggests.

“There’s an assumption that indigenous populations-particularly those in South America and in parts of Africa-are disappearing,” notes Lisa McAllister, a doctoral student in integrative anthropological sciences at the University of California, Santa Barbara. “But if you look at their reproductive rates and their fertility, what you see is that many groups’ population growth is actually astronomical.”


Some Tsimane populations have annual growth rates of 3 to 5 percent, and while that may seem low, it actually calculates to populations doubling in size in as few as 14 to 23 years.


“This is a problem, given their limited land and resources, and the fact that much of the land is already overused,” she says. “Many Tsimane already acknowledge the conservation issues that overpopulation is causing. For example, Tsimane commonly complain that they need to go farther and deeper into the forest to find animals to hunt; and close to town, farmland is in short supply.”


And yet, despite claims by both men and women that they want to have fewer children, and despite having better access to education and contraception, fertility rates among Tsimane women remain high-on average, nine births over a woman’s lifetime and more of those children are surviving.

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