ABSTRACT: BACKGROUND:Identifying modifiable risk factors for neuropsychological correlates of attention deficit hyperactivity disorder (ADHD) in early childhood can inform prevention strategies. Prenatal inflammatory states, such as maternal asthma and other atopic disorders, have been increasingly linked to enhanced risk for neurobehavioral disorders in children, with some studies suggesting sex-specific effects. OBJECTIVES:To assess the association between maternal active asthma and/or atopy in the antenatal period and child symptoms of ADHD during mid-childhood and, given the male-bias in ADHD prevalence, to examine modifying effects of child sex. STUDY DESIGN:The study sample includes 250 maternal-child pairs enrolled in the Boston-based Asthma Coalition on Community, Environment and Social Stress (ACCESS) pregnancy cohort. We defined antenatal active atopy based on maternal report of current asthma, allergic rhinitis or atopic dermatitis during and/or in the year before pregnancy. When children were approximately 6?years old, mothers completed a battery of standardized child behavior rating scales designed for evaluating symptoms of ADHD. We used multivariable quantile regression to assess the relations between maternal antenatal atopy and symptoms of ADHD among children. RESULTS:In adjusted models, maternal atopy was significantly associated with greater risk for ADHD behaviors, as indicated by scores on the Conners' Parent Rating Scale-Revised ADHD index (??=?3.32, 95% CI: 0.33, 6.32). In sex-stratified models this association was stronger among girls (5.96, 95% CI?=?0.95, 10.96) compared to boys (-2.14, 95% CI?=?-5.75, 1.45, p-interaction?=?0.01). Among girls, we observed a similar finding for the Behavior Assessment System for Children 2nd Edition Parent Rating Scale Attention Problems subscale (??=?7.77, 95% CI?=?1.57, 13.97). Results from other outcome subscales were similar in magnitude and direction, however, associations did not reach statistical significance at the p?=?0.05 level. CONCLUSIONS:Maternal antenatal active atopy may be a risk factor for the development of ADHD-like symptoms, especially among girls.