Use of opioids among pregnant women 1997-2016: A Danish drug utilization study

Use of opioids in pregnancy is of concern yet little is known on opioid prescription patterns in Denmark. The aim of this drug utilization study was to describe prescription patterns for opioids during pregnancy in Denmark from 1997 to 2016.

Using the nationwide health care registers, we obtained information on all women with a registered pregnancy in the period 1 January 1997 to 31 December 2016. Opioids were grouped in four: opioids (N02A except codeines), opioid dependency medications (N07BC), cough medications (R05DA except codeines), and codeines (N02AJ06, N02AJ07, N02BA75, and R05DA04). We used logistic regression analyses to identify factors associated with opioid use in pregnancy and cumulative oral morphine equivalent (OMEQ) to estimate volume of use in pregnancy.

Prescription patterns were similar for women with live births, non-live births, and terminations. Total use of opioids among women with live born deliveries remained stable at 19.8 per 1000 pregnancies from 1997 to 2016. Codeine use declined from 2008 onwards, while use of other opioids increased from 2007 onwards. This was dominated by a threefold increase in tramadol use (2.0-7.6 per 1000 pregnancies with live births). Codeine was the most used opioid, followed by tramadol and codeine combined with paracetamol. The number of women, who used opioids before pregnancy and continued into their pregnancy, was reduced as the pregnancy progressed. The cumulative oral morphine equivalent during pregnancy was stable until 2007, after which, use prior to pregnancy and during the first two trimesters increased. The odds ratios for opioid use were higher in pregnancies of women of lower socioeconomic status or older age. For live births, odds ratios for opioid use in pregnancy were higher among women with obesity or smoking.

Overall use of opioids was stable from 2007 to 2016. This covers a decline in the use of codeine, but a 3-fold increase in tramadol. The number of pregnant women who continued use throughout pregnancy decreased, while OMEQ among persistent users increased. The real-world data suggest an unmet need of specific focus in local Danish Outpatient Clinics and Multidisciplinary Pain Centers both pre-conceptionally and during pregnancy.