There's a Parasitic Worm in Bolivia That's Making Women Have More Children

A new parasite-centric discovery could lead to an advance in fertility medicine. The BBC reports that researchers have found a correlation between a certain type of roundworm infection and the number of children born to indigenous women in Bolivia.

From The BBC:

A study of 986 indigenous women in Bolivia indicated a lifetime of Ascaris lumbricoides, a type of roundworm, infection led to an extra two children.

Researchers, writing in the journal Science, suggest the worm is altering the immune system to make it easier to become pregnant.

How the worm is altering the immune system hasn’t yet been properly researched, but the scientists conducting the study were surprised to find that over 70 percent of the population was infected with it, possibly leading to larger family sizes. They surmise that being infected with the worm may make it harder for one’s immune system to reject the baby growing inside—and thus make the woman’s body “more friendly” towards pregnancy.

Not all worms are created equal, though.

But while Ascaris lumbricoides increased fertility in the nine-year study, hookworms had the opposite effect, leading to three fewer children across a lifetime.

The connection between this roundworm and increased fertility is, of course, far too tenuous for anyone to reasonably go worm hunting a la Maria Callas, who, according to legend, lost a whole bunch of weight by downing tapeworms.