A Swedish retrospective study investigated the association between the use of prescription opioid analgesics during pregnancy and developmental disorders in children. The study followed 1,267,978 children born between 2007 and 2018, of which 4.4% were exposed to opioids during pregnancy. At age 10 years, the cumulative incidence of autism spectrum disorder was 2.0% in non-exposed children, 2.9% in low-dose children, and 3.6% in high-dose opioid children. In initial analyses, high doses of opioids appeared to increase the risk of autism spectrum disorder and attention deficit disorder, but when the researchers used additional comparison methods, these associations weakened significantly or disappeared altogether. In particular, when comparing children whose parents used opioid medications before, but not during, pregnancy, the risk nearly equalized. The authors conclude that while high opioid doses cannot be completely ruled out as a risk factor, the results suggest that confounding factors may largely explain the observed increased risks.