Original studyBMJ Mental Health, 2026Read the paper →
Girls with attention deficit hyperactivity disorder, or ADHD, are often diagnosed years later than boys, and many reach their teens without support. The condition affects attention, planning, and impulse control, which can shape choices about sex and contraception. A large Swedish study now suggests that these girls face a much higher risk of unwanted pregnancy and sexually transmitted infections, and that staying on medication for longer is linked to a lower risk.
Researchers at Karolinska Institutet, Uppsala University, Danderyd Hospital, and Shenzhen University used healthcare records from the Stockholm region. The findings appear in BMJ Mental Health. The team followed 18,776 girls aged 4–20 who were diagnosed with ADHD or first given ADHD medication between 2011 and 2021, and compared them with 93,880 girls without ADHD of the same age and social background.
The study looked at two outcomes recorded before the age of 20: a sexually transmitted infection, counting a wide range from chlamydia to HIV, and a healthcare visit for an unwanted pregnancy, including abortion. The median age when follow-up began was 13.
Among girls with ADHD, 1,787 had one of these outcomes recorded, a rate of 29.3 per 1,000 person-years, a measure that allows for how long each girl was followed. The rate among girls without ADHD was 15.2. After allowing for other health conditions, earlier medication use, and earlier healthcare visits, girls with ADHD were about 70% more likely to have one of these outcomes, with the risk roughly doubled for unwanted pregnancy and 60% higher for infections.
The higher risk did not simply reflect other mental health problems. Girls with ADHD but no anxiety, depression, or substance use disorder still had about twice the risk of girls with none of these conditions. The highest risk was seen in girls who also had a substance use disorder, at more than four and a half times that of girls with none of these conditions.
Within the ADHD group, the team then looked at how long each girl had taken medication. Compared with a year or less of treatment, longer use was linked to lower odds in a dose-response pattern, although the step to one to two years was not statistically significant. Girls who had taken medication for more than five years had odds about a third lower.
The researchers suggest that medication may improve planning and self-control, which could make consistent contraception easier, and earlier work has linked it to fewer drug and alcohol problems. Girls who never took medication also had a lower risk than those treated for a year or less, probably because of differences such as symptom severity.
The study has limits. Records show prescriptions that were filled, not whether tablets were taken, and symptom severity could not be measured. Girls who stayed on treatment longer may have had more family support, and girls with ADHD saw doctors more often, so more of their outcomes may have been picked up.
Sweden offers free, confidential testing for infections and pregnancy at youth clinics, and abortion is free, so the results may not apply everywhere. The team says doctors treating teenagers with ADHD could consider adding sexual health advice and screening to their care.
Girls with ADHD face higher risks of unwanted pregnancy and infections, but longer medication use is linked to lower risk.
