Final answer:
Infertility is the inability of a sexually mature adult to reproduce by natural means. It is defined as the failure to achieve a successful pregnancy after at least one year of regular, unprotected sexual intercourse. In the case of the 28-year-old woman, her irregular menstrual cycles and inability to conceive after a year of trying may indicate potential infertility.
Step-by-step explanation:
Infertility is the inability of a sexually mature adult to reproduce by natural means. It is defined scientifically and medically as the failure to achieve a successful pregnancy after at least one year of regular, unprotected sexual intercourse. Infertility may be primary or secondary, depending on whether the individual has never achieved a successful pregnancy or has had a successful pregnancy in the past. In the case of the 28-year-old woman, her irregular menstrual cycles and inability to conceive after a year of trying may indicate potential infertility.