--- - |2+ There is an emerging body of evidence demonstrating that maternal obesity at the time of conception increases the risk for Autism Spectrum Disorders (ASD) among offspring. We explored whether pre‐pregnancy weight was related to autistic‐like traits among offspring not diagnosed with ASD. A large sample of women, recruited during the second trimester of pregnancy, had their height measured and reported their pre‐pregnancy weight. These measurements were then converted to a Body Mass Index (BMI) using the formula: (weight in kilograms)/(height in metres2). At 19–20 years of age, 1238 offspring of these women completed a measure of autistic‐like traits, the Autism‐Spectrum Quotient (AQ). Regression analyses identified a positive association between increasing maternal pre‐pregnancy BMI and increasing AQ Total Score amongst offspring; this association was maintained even after controlling for a range of variables including maternal/obstetric factors (age at conception, education, smoking, alcohol consumption, hypertensive diseases, diabetes, threatened abortion), paternal BMI at pregnancy, and child factors (parity, sex) (P < .01, R2=.03). Chi‐square analyses found that women with pre‐pregnancy obesity (BMI ≥ 30) were more likely to have offspring with high scores (≥26) on the AQ (P = .01). Follow‐up binary logistic regression analyses also accounting for the same obstetric and sociodemographic variables found that the offspring of women with pre‐pregnancy obesity were at a statistically significantly increased risk of having high scores (≥26) on the AQ (OR: 2.80; 95% CI: 1.06, 7.43). This study provides further evidence that maternal pre‐pregnancy obesity is associated with autism‐like behaviors in offspring. Lay Summary The current study explored whether pre‐pregnancy weight was related to autistic‐like traits among offspring not diagnosed with ASD. We found that pre‐pregnancy body mass index in women is associated with the amount of autistic‐like traits in their children in early adulthood. Specifically, women who were obese at the time of conception were more likely to have a child who had high levels of autistic‐like traits in early adulthood. - Autism Research, EarlyView.