Women who experience high levels of stress are less likely to conceive children.
Researchers at Ohio State University's Wexler Medical Center say women who have a high level of a known stress-indicating protein in their saliva are 29 percent less likely to become pregnant than other less-stressed women.
Women are also more likely to be defined as infertile while levels of the protein remain high.
Researchers say the study points to a need for women who want to become pregnant to use stress-reduction techniques to enhance their chances.
The study appears in the journal "Human Reproduction."