Substantial rise in antinausea medicine use during pregnancy, New Zealand study shows
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There has been a fivefold increase in the use of antinausea medicines during Aotearoa New Zealand pregnancies, a University of Otago—Ōtākou Whakaihu Waka-led study has found.
Published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, the research used anonymized national health data to review prescribing patterns in 1.37 million pregnancies from 2005 to 2019.
In 2005, 4.1% of pregnant individuals in Aotearoa used antinausea medicine in their first trimester of pregnancy; by 2019, use had increased to almost 20%.
Co-author Dr. Sarah Donald, of Otago's Department of Public Health, Dunedin, says nausea and vomiting during pregnancy is very common, but the substantial impact it has on affected individuals has historically been underrecognized and undertreated, so the increase is not surprising.
The most commonly dispensed antinausea medicine was metoclopramide, with exposure rising from 3.1% to 12.4% of pregnancies over the study time frame.
Use of another medicine, ondansetron, increased from almost no use (0.1%) to 9.1%.
"We were amazed at how quickly the use of ondansetron has become common during pregnancies here in New Zealand," Donald says.
Ondansetron is a very effective antinausea medicine that was developed for treating nausea caused by cancer treatments. However, it has not been approved to treat nausea in pregnancy, and such use is considered 'off-label.'
"Most clinical guidelines from the study period recommended ondansetron only if other antinausea medicines had been ineffective. But what we saw was, over time, its use as a first-line treatment also increased.
"Loosening of prescribing restrictions over time, and the fact that it comes in an easy-to-take dissolvable tablet, have probably contributed to its rising popularity for treating nausea in pregnancy. Newer guidelines now recommend ondansetron as one option for first-line treatment in those with moderately severe symptoms."
Donald says nausea and vomiting in pregnancy affects up to 70% of pregnancies and, as with any medicine used during pregnancy, the safety of antinausea medicines needs to be considered.
Several previous studies have suggested that ondansetron exposure during the first trimester of pregnancy may be associated with a very small increase in the risk of birth defects such as heart defects and cleft lip/palate. However, other studies have not found increased risk, and the evidence overall is unclear.
"With increasing ondansetron exposure in early pregnancy, further information on its safety would be helpful to better guide treatment decisions," Donald says.
More information
Sarah Donald et al, Dispensing of Antiemetics During Pregnancy in Aotearoa New Zealand, 2005–2020, Australian and New Zealand Journal of Obstetrics and Gynaecology (2026). DOI: 10.1111/ajo.70157
Key medical concepts
AntiemeticsOndansetronMetoclopramideCongenital Abnormalities
Clinical categories
Obstetrics & gynecologyPregnancyClinical pharmacology Provided by University of Otago Who's behind this story?
Sadie Harley
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