Final answer:
The nurse should inform the client that a sign of ovulation is the thickening of cervical mucus, which assists sperm movement and can help predict ovulation.
Step-by-step explanation:
A sign of ovulation that the nurse should inform the client about is the thickening of cervical mucus. As ovulation approaches, cervical secretions usually increase in amount and become thinner, which facilitates the movement of sperm through the cervical canal. This change in cervical mucus can predict ovulation ahead of time. While basal body temperature (BBT) rises slightly after ovulation has occurred, it only indicates ovulation after the fact and therefore is not as effective for planning or preventing pregnancy. Additionally, home ovulation predictor kits are available for predicting ovulation by measuring the level of luteinizing hormone (LH) in the urine.