Global trends in analgesic opioid use in pregnancy: A retrospective cohort study.

Pain is common during pregnancy yet there are few contemporary studies of opioid utilisation in pregnancy. We aimed to describe prescription analgesic opioid use during pregnancy across four regions: Oceania [New South Wales (Australia), New Zealand], North America [Ontario (Canada), United States (US)], Northern Europe [Denmark, Finland, Iceland, Norway, Sweden, United Kingdom (UK)], and East Asia (Hong Kong, South Korea, Taiwan). We applied a common protocol to population-based data to measure analgesic opioid dispensing or prescriptions during pregnancy prior to birth in 2000-2020. Populations captured included those with public and private insurance in the US, a sample of primary care practices in the UK and whole-of-population cohorts in the remainder. We examined prevalence of use, defined as at least one dispensing or prescribing and estimated trends over time. We described use by sociodemographic- and pregnancy characteristics. Among a total of 20,306,228 pregnancies, 1,115,853 (55 per 1000) had at least one analgesic opioid dispensing or prescription, ranging from 4 per 1000 in the UK to 191 per 1000 in the US publicly insured population. We observed the greatest relative decrease in prevalence in Hong Kong (prevalence ratio 0.2; 95% CI 0.1-0.2 between 2005 and 2020) and greatest increase in Iceland (prevalence ratio 4.4; 95% CI 3.7-5.2 between 2004 and 2017). Codeine and tramadol were among the three most prevalent opioids in most populations. In a sensitivity analysis defining opioid use as two or more opioid dispensing or prescribing events, the prevalence of opioid use across populations was 17 per 1000. In this large multinational study, we observed wide global variation in prevalence of analgesic opioid use in pregnancy, yet patterns of use by sociodemographic- and pregnancy characteristics were relatively consistent. Analgesic opioid use remained stable or downward trending over time in most, but not all, countries.