Postpartum Psychotropic Treatment Patterns and Breastfeeding: Nationwide Clustering Study

Postpartum psychotropic medication use is heterogeneous, comprising continuation of prenatal treatment, initiation, transient use and complex polypharmacy. Prior studies have reported the prevalence of potential infant exposure to psychotropics via breast milk, but characterisations better capturing the heterogeneity of this exposure are lacking. We aimed to identify distinct postpartum psychotropic treatment patterns using hierarchical clustering accounting for medication type, timing and polypharmacy, and to describe breastfeeding characteristics across these patterns.

Population-based cohort study of mothers using psychotropics during the first postpartum year using linked Danish national registers 2012-2023. From a source population of 659 866 mother-child pairs with live-born singleton births, 38 528 mothers redeemed at least one psychotropic prescription during the first postpartum year and comprised the study cohort. Weekly psychotropic use was defined by redeemed prescriptions using prescribed daily dose assumptions. Hierarchical agglomerative clustering (tame R package) identified distinct treatment patterns based on medication type, timing and polypharmacy. The number of patterns was determined from interpretability, size and examination of the hierarchical dendrogram. Exclusive breastfeeding prevalence and duration were described across patterns among pairs with recorded breastfeeding habits (64%).

Eight distinct treatment patterns were identified, differing in psychotropic type, timing and polypharmacy. Three SSRI-dominated patterns (24 225 pairs, 63%) ranged from increasing SSRI use (Pattern I; n = 11 731), through continued SSRI use with high persistence (Pattern II; n = 7167), to mixed use involving SSRIs and other psychotropics (Pattern III; n = 5327; 48% using three or more medications). The remaining five patterns (14 303 pairs, 37%) were dominated by benzodiazepine-related drugs, other antidepressants, centrally acting sympathomimetics, antipsychotics or complex mixed use, ranging from late-initiated benzodiazepine-related use (Pattern IV; median initiation Week 27; persistence 13%) to early-initiated, highly persistent mixed use (Pattern VIII; median initiation Week 4; persistence 94%). Exclusive breastfeeding duration varied across patterns, with long-duration exclusive breastfeeding (181 days or more) highest in the SSRI-continued pattern (Pattern II, 10.6%) and lowest in the mixed-use-increasing and antipsychotics-sporadic patterns (Patterns III and VII, 5.1% and 5.2%).

Postpartum psychotropic treatment patterns are clinically heterogeneous and exclusive breastfeeding practices differ across treatment patterns.