Switching pattern and dose adjustment of antidepressants before and during pregnancy

The purpose of the study is to examine the switching pattern and dose adjustment of antidepressants (ADs) prescribed to women from six months before to six months during pregnancy in the Netherlands. The recorded dispenses or refills were collected from the University of Groningen IADB.nl pregnancy subset for all singleton pregnancies in which the mother received ≥ 1 prescription of an AD dispensed before pregnancy and was present in the database at least six months after conception. The rates of continuation, discontinuation, and switching between 2001 and 2020 were assessed for the ADs studied. The mean number of Defined Daily Doses (DDDs) of the most frequently continued ADs used was calculated both before and during pregnancy, and a paired t-test was used to test for significant changes. The continuation rates for AD users, especially for SSRI and SNRI continued users, increased over time from 27% and 19% (2001-2005) to 65% and 65% (2016-2020). The switching rate between ADs remained consistently low from the start of the study (2001-2005) at 2.0% to the end of the study (2016-2020) at 2.3%. Most women who switched between antidepressants during pregnancy received a different SSRI monotherapy (85%), followed by an SNRI (6%), a TCA (4%), and an "other AD" (4%). In most cases observed, the dose adjustment for the mean DDDs during pregnancy compared to the mean DDDs before pregnancy only changed little (less than 10%). Continued use of SSRIs among singleton pregnancies doubled over the study period. The low rate of AD switching and little changes in the DDD adjustment for most AD continuers indicate that pregnant women prefer to continue their prepregnancy medication rather than switch it. Most observed findings cohere with the Dutch national guidelines for antidepressant use during pregnancy.