Background: After cesarean delivery under spinal anesthesia with morphine, postoperative nausea and vomiting (PONV) may disturb maternal activity during breastfeeding and consequently reduce the successful rate of lactation. Prophylactic ondansetron may reduce the symptoms during 24 hours postdelivery.

Objective: We conducted the present study to evaluate if ondansetron can reduce the incidence of nausea and vomiting after spinal morphine during early rooming in breastfeeding. The present study also investigated the associated factors of nausea and vomiting, occurring in post-anesthesia care unit (PACU) and during breastfeeding.

Material and Method: In a randomized, double-blinded study, 158 healthy patients having cesarean delivery under spinal anesthesia with morphine 0.2 mg were randomized to have ondansetron 4 mg (ondansetron group) or normal saline (control group) intravenously immediately after delivery. The primary outcome was the incidence of nausea during the first rooming-in breastfeeding. The incidence within 24 hours, the score of severity by a four-point Likert Scale, the incidences of vomiting, and itching were also compared.

Results: Comparing the incidence of nausea between ondansetron and control groups, they were similar during the first breastfeeding (24.2% vs. 37.5%) and 24 hours postdelivery (3.8% vs. 10.0%), (p = 0.07 and 0.13). The number required the rescued antiemetic in the PACU in the ondansetron group was less (5.1% vs. 16.3%, p = 0.02), but the other observed incidences and severity of nausea were similar to the control group. By regression analyses, the factors that reduced the nausea incidence in the PACU were ondansetron administration (p = 0.04, adjusted OR 0.28, 95% CI 0.08 to 0.96), and the history of previous cesarean delivery (p = 0.04, adjusted OR 0.29, 95% CI 0.09 to 0.98). By contrast, postdelivery methylergometrine administration increased the incidence (p = 0.04, adjusted OR 3.24, 95% CI 1.01 to 10.40). At 24 hours postdelivery, only the history of PONV increased the incidence (p = 0.04, adjusted OR 2.72, 95% CI 1.04 to 7.12).

Conclusion: The incidence of nausea was reduced by prophylactic ondansetron in the PACU, but was not significantly different during breastfeeding on the same day and 24 hours postoperatively. Therapeutic ondansetron may be appropriate and an economical practice.

Keywords: Breastfeeding, Cesarean, Nausea, Ondansetron, Prophylaxis