From early to fewer first births: ADHD and family formation among young adults
Sanna Kailaheimo-Björkqvist, Niina Metsä-Simola, Mikko MyrskyläBackground
Attention-deficit/hyperactivity disorder (ADHD) is common and associated with relationship difficulties, which may influence entry into parenthood.
Methods
We used Finnish population register data to follow 759,430 individuals born in 1982–1993 and examined how ADHD is associated with the likelihood and timing of a first birth. ADHD was identified using healthcare diagnoses and prescription records. We estimated discrete-time event history models and sibling fixed-effects models to account for shared family background. All analyses were conducted separately for women and men.
Results
In models adjusted for age and birth cohort, ADHD was associated with a lower likelihood of a first birth (ages 18–38) (men OR 0.92; women OR 0.90). After adjusting for partnership characteristics, the association reversed (men OR 1.07; women OR 1.09). All age-stratified analyses showed that ADHD was associated with a higher likelihood of first birth at ages 18–23, but with a lower likelihood at ages 24–30 and 31–38, indicating earlier entry into parenthood among individuals with ADHD. Results from sibling fixed-effects models were broadly similar to the population-level estimates, suggesting limited confounding by shared family background.
Conclusions
ADHD is associated not only with earlier entry into parenthood but also with a reduced overall probability of having a first child. Accounting for partnership status is important, as it largely explains the negative association observed in age-adjusted models. These findings highlight partnerships as a key pathway linking ADHD to fertility outcomes.