Dave Barson

Background: Antiemetic use during pregnancy is rising in high‐income countries. Increasing use of antiemetics has also been documented in Aotearoa New Zealand (NZ); however, the specific antiemetics dispensed have not been reported. Aim: To describe patterns of antiemetic dispensing during pregnancy in NZ, 2005–2020. Materials and Methods: Community‐based antiemetic dispensings were linked with 1.37 million pregnancies in the New Zealand Pregnancy Cohort. The proportions of pregnancies in which there was at least one dispensing of any and of specific antiemetics were calculated for each trimester and calendar year. Maternal characteristics and the sequence in which unique antiemetic regimens were introduced were described for pregnancies with first trimester exposure. Results: First trimester antiemetic exposure increased from 4.1% to 19.7% of pregnancies between 2005 and 2019. Although metoclopramide was the most commonly dispensed antiemetic during Trimester 1 in all years (increasing from 3.1% to 12.4%), there was a substantial increase in ondansetron dispensing (0.1% to 9.1%). Ondansetron users were more likely than metoclopramide users to be European/Other and have a hospital admission for hyperemesis gravidarum. Metoclopramide and ondansetron monotherapy were first‐line regimens in 70.0% and 1.9% of pregnancies with Trimester 1 exposure between 2005 and 2010 versus 46.5% and 26.5% between 2016 and 2020. Conclusions: Ondansetron dispensing increased substantially over time. Further exploration of the context of ondansetron prescribing in NZ is warranted, as is further research into potential adverse outcomes.