1. Autism was diagnosed earlier in boys but later in girls, often during adolescence or adulthood.
2. Sex differences in autism diagnosis narrowed substantially over time.
3. Male-to-female diagnosis ratios approached one by age 20 years in recent cohorts.
4. Autism incidence increased across calendar periods for both sexes.
5. Findings suggest diagnostic bias rather than true sex differences in incidence.

Source: The BMJ study and editorial