Adult IQ predicted by age 2 for premature babies

"The results indicate that assessing two year olds who were born very preterm or very underweight and will provide a reasonably good prediction to what their adult IQ will be," says Dieter Wolke. (Credit: Nana B Agyei/Flickr)

The IQ of adults born very premature or of very low birth weight can be predicted when they are just a toddler, new research shows.

In contrast, the research found the IQ of adults who were born full-term couldn’t be accurately predicted until age six.

Previous studies have linked very premature birth and very low birth weight with impaired cognitive function from childhood and throughout adulthood. However until now it wasn’t clear how soon adult IQ can be predicted in these children

“We believe this is the first time a research paper has looked into the prediction of the IQ of adults over the age of 26 who were born very premature or with very low birth weight,” says Dieter Wolke, a psychology professor at the University of Warwick.

“The results indicate that assessing two year olds who were born very preterm or very underweight and will provide a reasonably good prediction to what their adult IQ will be.”

Across all assessments within the study very premature and very low birth weight children and adults had lower IQ scores than those born full-term, even when individuals with severe cognitive impairment were excluded from the comparisons. The findings are reported in the journal Pediatrics.

The study was conducted in southern Bavaria, Germany and followed children from birth into adulthood who were born between 1985-86. Called the Bavarian Longitudinal Study data gained on cognitive function were assessed with developmental and intelligence tests (IQ) at five and 20 months and at four, six, eight, and 26 years of age.

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Two-hundred-and-sixty babies born either very premature (before 32 weeks) or with very low birth weight (fewer than 1.5kgs) were compared with 229 babies who born full-term. Their results were not sex-specific, related to income or education, and were compared to the control group of adults who were born healthy in the same obstetric wards.

“Some children born very premature or with very low birth weight score low on cognitive tests but beat the odds and improve into adulthood”,” says Wolke.

“However many with persistent problems can be detected in the second year of life. Early identification of cognitive problems in these children may help to plan specialized therapeutic and educational interventions to help them and their families.”

Source: University of Warwick