Antidepressant Treatment in Pregnancy and Maternal Mental Health in the Postpartum Year: A Danish Registry Linkage Study in Pregnant Women with Obsessive‐compulsive Disorder

Background: Lacking real-world evidence regarding the benefits of antidepressant continuation, especially in preventing postnatal mental illnesses and potential negative outcomes of treatment discontinuation increases uncertainties for both clinicians and pregnant women in making their decision about the treatment. This is particularly true for obsessive-compulsive disorder (OCD) as most studies, to date, focus on other conditions such as depression and anxiety.

Objectives: To explore the preventative association of antidepressant treatment continuity in pregnancy on postpartum episode of OCD and mood/anxiety disorders in women with pre-existing OCD.

Methods: We identified 1,324 live-birth singleton pregnancies within women having outpatient/inpatient visits for OCD in the four years prior to pregnancy in the Danish registries linked data. Antidepressant exposure status was derived from data regarding antidepressant fills in the two years prior to pregnancy to delivery: (i) unexposed (n=449, 33.9%); (ii) discontinuers (n=346, 26.1%), i.e., pregnancies with antidepressant exposure before pregnancy only; (iii) continuers (n=522, 39.4%), i.e., pregnancies with antidepressant exposure before and during pregnancy. We estimated crude and weighted hazard ratio (HRs) of OCD episode and mood/anxiety disorder in the postpartum year using Cox proportional hazard models. Adjustment was done with inverse probability of treatment weighting.

Results: Before weighting, continuers had on average 2.26-fold higher risk (95%CI: 1.21; 4.23) of having postpartum OCD episode compared to unexposed. However, the elevated risk with antidepressant continuation faded away after weighting, leaving similar risks for an OCD episode compared to non-medicated (weighted HR range: 0.78-3.60) and discontinuers (weighted HR range: 0.69-2.62). Similarly, there was no difference in the risks of having postpartum episode of mood/anxiety disorders across antidepressant treatment groups. Yet the risk of having these conditions was three times higher in those pregnancies having only one prescription fill during pregnancy compared to unexposed.

Conclusions: Among pregnant women with pre-existing OCD, antidepressant continuers have similar risk for an OCD episode or mood/anxiety disorders diagnosis in the postpartum year compared unexposed and discontinuers before pregnancy. However, discontinuation during pregnancy may be associated with higher risks for these conditions.