Infection with a species of parasitic worm increases the fertility of women, say scientists. 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.

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Infection with a species of parasitic worm increases the fertility of women, say scientists. 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.