Are prenatal ultrasound scans associated with the autism phenotype? Follow-up of a randomised controlled trial.

Doctors randomly gave some pregnant women five extra ultrasound scans. The rest got the normal one or two.

Years later the team checked which children were diagnosed with autism or showed autistic traits.

Extra scans did not raise autism rates. Kids in both groups looked the same on social and behavior tests.

More ultrasound exposure simply did not matter.

Boets et al. (2011) and Stewart et al. (2018) also used prenatal ultrasound. They measured head size instead of scan count. All three studies end with the same bottom line: routine fetal ultrasound does not predict later autism.

Chien et al. (2019) found that problems like preeclampsia do link to steeper autism traits. That result might seem to clash with today’s paper, but the 2019 study looked at medical illness, not scan load. Different exposures, different answers—no real contradiction.

Granieri et al. (2020) used sibling comparisons to cancel out family genetics. Maternal smoking lost its apparent risk, just as extra ultrasounds lost theirs. Both papers show that stronger designs erase scary but false prenatal threats.

You can reassure worried parents: the standard scan schedule is safe. There is no evidence that additional scans cause autism, so medical need—not fear—should guide ultrasound orders. Keep referring for imaging when doctors need it; skip the extras when they do not.