Patterns of antidepressant prescribing during pregnancy between 1996 and 2018 using the Clinical Practice Research Datalink

Background Antidepressants are among the most common prescriptions in women of childbearing age and prescribing has increased in recent decades. Some evidence suggests that many women discontinue antidepressants on becoming pregnant. Understanding patterns of antidepressant prescribing in pregnancy is crucial for both clinicians and those researching associations between antidepressant use during pregnancy and outcomes.

Methods Using the Clinical Practice Research Datalink (CPRD) Pregnancy Register, we defined a cohort of eligible pregnancies and using primary care prescription data, identified which out of these were prescribed antidepressants in the 12 months before, during, and the 12 months after pregnancy. Prevalent and incident users were categorised among those who were prescribed antidepressants during pregnancy. Prevalent users were those who had at least one prescription of antidepressants in the 3 months prior to pregnancy and incident users were those who did not have any antidepressant prescriptions in the 3 months prior to pregnancy. We investigated patterns of prescribing within pregnancy among those two groups: discontinuation, dose changes, medication switching, and continuation with no changes to their regimen.

Results Between 1996 and 2018, 30,804 pregnancies were exposed to antidepressants, of which 24,219 (79%) had been prescribed antidepressants in the 3 months prior to pregnancy (prevalent users). Incident users during pregnancy (no prescriptions in the 3 months before the start of pregnancy) made up the remaining 21%. Discontinuation of antidepressants during pregnancy was most common (78% and 81% for prevalent and incident users, respectively). Among those who did not discontinue their antidepressants during pregnancy, decreasing dose was more common among prevalent users, however among incident users, increasing dose was more common. In both prevalent and incident users, not making any changes to their regimen was the most common pattern (47% and 69%, respectively). When investigating the 12 months after pregnancy, the majority of those who discontinued during pregnancy resumed antidepressants in the immediate postpartum period (64%).

Conclusion The majority of women in the UK prescribed antidepressants in pregnancy are prevalent users who already have prescriptions for these medications before their pregnancy. A substantial proportion of these prescriptions are discontinued in early pregnancy but are reinitiated after the end of pregnancy.