From early to fewer first births: ADHD and family formation among young adults

Background: Attention-deficit/hyperactivity disorder (ADHD) is common and linked to relationship difficulties. It may affect the likelihood and timing of parenthood, yet its implications for fertility remain unclear. Methods: Using Finnish population registers, we followed 759,430 individuals born in 1982–1993 to examine how ADHD is associated with the likelihood and timing of a first birth among young adults. ADHD diagnoses were identified from healthcare and prescription records. Discrete-time event-history models were estimated separately for women and men. Interaction analyses assessed whether a partner’s ADHD modified associations. Results: In age- and cohort-adjusted models, ADHD was linked to lower odds of a first birth (men OR 0.92; women OR 0.90), but after adjusting for partnerships the association was reversed (men OR 1.07; women OR 1.09). At ages 18–23, ADHD was associated with a higher likelihood of having a first birth, whereas an opposite association was observed at ages at 24–30 and 31–38. Thus, ADHD was related to a higher likelihood of first birth at young ages and lower likelihood at older ages. Both partners having ADHD does not seem to intensify the association. Conclusions: ADHD is associated with earlier entry into parenthood but a lower risk of first birth at later ages. The results highlight the importance of accounting for partnerships: before this adjustment, ADHD was negatively related to the likelihood of becoming a parent, whereas after adjusting for partnerships the association reversed. This underscores partnership formation as a key pathway and suggests that supporting stable unions may help mitigate ADHD-related disparities in first births. Keywords: first birth, child, family formation, ADHD, partnerships