Purpose: The study aimed to describe the dispensing of benzodiazepines and benzodiazepine-related drugs (z-hypnotics) to pregnant women and to study the characteristics of these women and the extent of co-medication.
Methods: A population-based cohort study was conducted based on the linkage of nationwide registries: the Medical Birth Registry of Norway and the Norwegian Prescription Database. The data covers dispensed drugs to women 3 months prior to, during and after pregnancy. The study population consisted of 345,703 singleton pregnancies during a period starting 1 April 2004 or later and ending before 1 January 2011.
Results: In 5,135 (1.5 %) of the pregnancies, the women were dispensed a benzodiazepine or z-hypnotic at least once. Of these, 68.5 % filled just one prescription for the duration of the pregnancy. Prevalence was lower in pregnancy than before and after pregnancy. The median total amount of benzodiazepines and/or z-hypnotics dispensed during pregnancy was 15 defined daily doses (DDDs), while the 25 % receiving the largest amounts got 40 DDDs or more. Five hundred eleven women, the 10 % that were prescribed the largest amounts during pregnancy, received a median amount of 220 DDDs. Women receiving these drugs were older, more often smokers, without a partner and suffering from chronic disease. Of the medicated pregnant women, 19.6 % and 19.3 % were also prescribed an opioid and antidepressant, respectively.
Conclusions: The use of benzodiazepines and z-hypnotic drugs during pregnancy was not very prevalent in Norway. However, our findings imply that there is a substantial number of pregnancies where these drugs are dispensed often and/or in large quantities and where co-medication occurred.