Background: The study aim was to investigate the efficacy of an intervention designed to provide a basis for informed choices about future parenthood to special upper secondary school students with intellectual disabilities. Methods: A randomised trial with a waiting list control group was used. In total, 108 special upper secondary school students with mild or moderate intellectual disabilities, age 16-21 years, provided informed consent and participated. The intervention included education using the Parenting Toolkit and a Real Care Baby simulator. The analyses included 91 students (intervention group n = 46, 24F/22M; control group n = 45, 26F/19M). Results: The result showed that intervention group changed their attitudes to future parenting, from 'do not know' to 'know', significantly more than control group. The intervention increased knowledge levels in the intervention group. Conclusions: The intervention group showed increased ability to make informed choices and decisions about parenthood.