Maternal ADHD Diagnoses Before and After Childbirth: A Danish Population-Based Cohort Study

Objective: The rates of women of reproductive age diagnosed with ADHD have increased significantly. However, little is known about how pregnancy, childbirth, and the postpartum period influence ADHD related problems, help-seeking behaviors or the timing of ADHD diagnosis. This study aimed to investigate incident ADHD diagnoses among women from 5 years before to 5 years after childbirth. Method: The population-based cohort study utilized Danish nationwide registers to identify mothers of all childbirths between 2010 and 2018. ADHD diagnoses, defined as ICD-10 codes (F90 or F98.8) or redemption of ADHD medication prescriptions, were recorded during 1994 to 2023. Women who received an ADHD diagnosis prior to the five-year pre-birth period were excluded. We estimated calendar-year adjusted incidence of first-time maternal ADHD diagnoses using Poisson regression, and compared incidence across pre-pregnancy, pregnancy, postpartum up to 2 years, and 2 to 5 years postpartum, reporting adjusted incidence rate ratios (IRRs). Analyses included psychiatric comorbidities and non-ADHD psychotropic medication use prior to an ADHD diagnosis, for women diagnosed with ADHD postpartum. Results: The study included 363,904 mothers with a total of 524,936 childbirths. ADHD incidence rates decreased significantly during pregnancy (IRR = 0.28, 95% CI [0.22, 0.37]), remained lower than the pre-pregnancy period 2 years postpartum (IRR 0.82, 95% CI [0.74, 0.92]), and increased significantly above pre-pregnancy levels 2 to 5 years postpartum (IRR = 1.24, 95% CI [1.13, 1.35]). Among mothers diagnosed with ADHD postpartum, 53.9% had an in- or outpatient contact to psychiatric services or redeemed non-ADHD psychotropic medication prescriptions, in the period from childbirth until ADHD diagnosis. Conclusion: Incident ADHD diagnoses among women giving birth increased postpartum above pre-pregnancy levels, with peak rates observed between 2 and 5 years after childbirth. These findings highlight the postpartum period as a potential critical window of ADHD symptom worsening, underscoring the need for targeted mental health screenings and support for women during the years after childbirth.