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Patterns of prescription medicine dispensing before and during pregnancy in New Zealand, 2005–2015

Wednesday 10 June 2020 4:16pm

The use of prescription medicines by pregnant women in New Zealand increased substantially between 2005 and 2015.

Sarah Donald image 2020
Lead author, Dr Sarah Donald.

In a national study by researchers from the Pharmacoepidemiology Research Network, anonymised pharmaceutical dispensing data were linked with almost 875,000 pregnancies to investigate patterns of medicine use during pregnancy. Dr Sarah Donald, lead author of the study, said “In 2005, 37% of pregnant women were dispensed at least one prescription medicine; by 2015 that number had increased to 67%, and these figures don’t include supplements like folic acid and iron, which many women in the study also received.”

“When we looked at the different types of medicines used, the increased use was seen pretty much across the board, not just confined to a handful of medicines,” Dr Donald reported. According to the study, recently published in PLOS ONE, antibiotics were used in a quarter of pregnancies, pain relief in 17% and anti-nausea medication in 11%.

The average number of different medicines used during pregnancy was 3.1, similar to findings from Canada, Denmark and Norway. However, unlike some studies overseas, the Otago researchers did not find very strong relationships with use of at least one medicine and the age, ethnicity, or smoking status of the mother. Women who were obese were more likely to use a prescription medicine during pregnancy than women who were a healthy weight.

Is this increased medication exposure cause for concern? “The use of medicines during pregnancy is not an issue if the balance of benefits and harms to both the mother and her fetus has been appropriately considered first. However, the long-standing exclusion of pregnant women from clinical drug trials means that the pregnancy safety profile for most medicines is not well established, which makes this balance difficult to assess,” replied Dr Donald.
This study was undertaken as part of Dr Donald’s PhD research, and was funded by a Clinical Research Training Fellowship from the Health Research Council of New Zealand.

Publication details

Donald S, Sharples K, Barson D, Horsburgh S, Parkin L. Patterns of prescription medicine dispensing before and during pregnancy in New Zealand, 2005–2015. PLoS ONE 15(6): e0234153.