A new study by the UC Davis MIND Institute finds a connection between gestational age and attention deficit/hyperactivity disorder (ADHD) symptoms in children with Down syndrome. The research, published in Scientific Reports, focused on children born at 35 weeks gestation or older. It found that earlier gestational age was linked to increased ADHD symptoms later in childhood. Gestational age is the length of time a fetus has developed since the beginning, or gestation, of a pregnancy.