From the Discussion section:

The results of our meta-analysis representing more than 70,000 children of six European population-based birth/child cohorts indicated that children prenatally exposed to acetaminophen were 19% and 21% more likely to subsequently have ASC and ADHD symptoms within the borderline/clinical range, respectively, compared with non-exposed children. The association with ASC was attenuated after omitting the largest cohort but remained positive. When stratifying by sex, these associations were slightly stronger among boys compared to girls but positive associations with effect sizes of similar magnitude were observed in both strata, especially in the case of ADHD. Postnatal exposure to acetaminophen was not associated with either of the outcome, thought there was evidence of between-study heterogeneity for the association with ASC symptoms.

From the Outcomes section:

ASC and ADHD symptoms were assessed using validated parent-reported questionnaires or linked hospital records. Autistic symptoms were assessed using the Development And Well-Being Assessment (DAWBA) [18] (ALSPAC), the Pervasive Developmental Problems (PDP) subscale of the Child Behaviour Checklist for Toddlers (CBCL1½–5) [19] (GASPII and The Generation R Study), the Childhood Autism Spectrum Test (CAST) [20] (INMA) and an ASC scale derived from the CBCL for 6–18 (CBCL6–18) [21] (RHEA). ADHD symptoms were assessed using the Development and Well-Being Assessment (DAWBA) [18] (ALSPAC); the Conner’s Parent Rating Scale Revised short form (CPRS-R:S) [22] (The Generation R Study), the Hyperactivity/Inattention subscale of the Strengths and Difficulties Questionnaire (SDQ) [23] (DNBC), the Attention Deficit and Hyperactivity problems subscale of the CBCL1½-5 and CBCL6/18 (GASPII and RHEA), and the ADHD Criteria of DSM-IV (DSM-ADHD Questionnaire) [24] (INMA). Higher scores indicate more symptoms.