Pediatricians are far more likely to screen children for developmental delays than they were in the early 2000s, but many still fail to follow guidelines recommending that all kids be checked.

A study released Monday shows that 63 percent of pediatricians reported utilizing standardized developmental screening tools in 2016. That’s up dramatically from just 21 percent in 2002.

However, it falls short of the American Academy of Pediatrics recommendation that doctors screen all children at 9, 18 and 30 months.

The research published in the journal Pediatrics this week is based on the results of a routine survey sent to more than 1,600 members of the national pediatrics group in 2002, 2009 and 2016.

In addition to a growing number of physicians saying that they conducted screening over the time period studied, pediatricians also increasingly said that they were “very likely” to refer children who showed signs of developmental delay for early intervention or to a specialist. And, the study found that kids were referred for a wider range of conditions.

Screening is seen as the best way to flag children at risk for developmental delays early so that they can begin treatment. Intervention is considered most effective the sooner it begins.

“The encouraging results of this study show increased use of standardized developmental screening tools since 2002, with nearly two-thirds of pediatricians now performing standardized screening of children for developmental problems,” wrote Paul Lipkin of the Kennedy Krieger Institute and his colleagues in their findings. “However, one-third of pediatricians are not completing standardized screening, with barriers remaining, leaving many children unscreened for developmental disorders and potentially resulting in delayed identification and treatment of problems that may affect children and families for a lifetime.”

The biggest barrier to conducting developmental screening is time limitations, according to the doctors surveyed.

Researchers behind the study said more needs to be done to improve screening and referral systems in order to further increase screening rates. In particular, they noted that incorporating screening tools and referral tracking into electronic medical record systems could help.