Examination of sex differences in a large sample of young children with autism spectrum disorder and typical development.

The team looked at a large group of toddlers and preschoolers. Some had autism. Some were typical.

They checked if boys and girls scored differently on language, play, and autism tests.

Boys and girls looked almost the same. No big gaps showed up on any test.

The authors say early autism looks alike for both sexes.

Andersson et al. (2013) and Crawford et al. (2015) also found no overall sex gap. They used smaller, matched groups. The new study shows the null result holds in a big natural sample.

Fleury et al. (2018) seems to disagree. They saw more social-communication problems in girls. Their kids came from the community and were a bit older. Sampling setting, not biology, likely explains the clash.

Ros-Demarize et al. (2020) later found girls can show stronger social-communication deficits, but only on some screens. They warn common checklists may miss girls. The target paper used broad tests, so it did not pick up that nuance.

If you test a toddler for autism, treat boys and girls the same at first. Use the same cut scores and watch for the same red flags. Later, if the child almost meets criteria, run a second social-communication probe, especially for girls. Update your screening packet now: keep one set of norms, but add a brief parent question about subtle social gaps.