Hyperemesis gravidarum (HG) represents the most severe end of the nausea and vomiting of pregnancy spectrum. It has a reported incidence of approximately 0.3–3% of pregnancies and is the most common cause of hospitalization in early pregnancy and the second most common cause of hospitalization in pregnancy overall. In June 2024, the ACOG published a Clinical Expert series summarizing the inpatient management of HG. In that guidance, it describes mirtazapine as an “alternative pharmacologic” option. How effective is this medication compared to ondansetron? A new study (published ahead of print on 12/30/25 and officially out June 2026), out of Denmark, sheds some new light on this medication. This trial is the first double-blind RCT comparing mirtazapine to ondansetron AND placebo. Although a BIG limitation of this study exists (which we will discuss), it does provide some interesting insights. Listen in for details.

1. (ACOG CES) Clark, Shannon M. MD; Zhang, Xue MD; Goncharov, Daphne Arena MD. Inpatient Management of Hyperemesis Gravidarum. Obstetrics & Gynecology 143(6):p 745-758, June 2024. | DOI: 10.1097/AOG.0000000000005518

2. Ostenfeld, AnneDroogh, Marjoes et al.Mirtazapine or ondansetron for hyperemesis gravidarum. A randomized placebo-controlled trial. American Journal of Obstetrics & Gynecology, June 2026