Abstract: Fertility in females, especially human females, is evaluated by contacting a mucin-containing body fluid such as saliva with a fertility evaluation medium comprising an anthocyanin pigment and a substrate which facilitates generation of a color response in the pigment, in the presence of vaginal fluid or substances similar to those found in the vaginal fluid, especially ascorbic acid and sugars. A resulting color change in the fertility evaluation medium can be used to determine whether the female is not fertile at that time, whether fertility is imminent in the female, or whether the female actually is fertile.