Which of the following is the most significant risk factor for postoperative nausea and vomiting

Postoperative nausea and vomiting is most common in women, young people, and patients who have received opioids during surgery. Surprisingly, perhaps the one advantage of smoking is that smokers tend to have less postoperative nausea and vomiting than nonsmokers. Similarly, the incidence of postoperative nausea and vomiting is lower in the geriatric population.