Dr Robert Eves Research Associate at Universität Bielefeld Honorary research fellow at the University of Warwick Guest researcher at DIW Berlin

Birthweight, Gestational Age and Later Cognitive Performance

MedicalResearch.com Interview with:

Dr Robert EvesResearch Associate at Universität Bielefeld Honorary research fellow at the University of Warwick Guest researcher at DIW Berlin

Dr. Eves

Dr Robert Eves
Research Associate at Universität Bielefeld
Honorary research fellow at the University of Warwick
Guest researcher at DIW Berlin

MedicalResearch.com: What is the background for this study?

Response: When an infant is born their birthweight percentile is often calculated. This indicates how big the infant is relative to other infants born at the same gestational age (weeks of pregnancy). In long-term follow-up of at-risk infants, being born below the 10th percentile has been considered a risk factor for later cognitive development.

However, we thought that this above or below the 10th percentile cut-off was unlikely to reflect the true association between birthweight percentiles and later cognitive development.

First of all, we thought that it was unlikely that there would be a dramatic difference between someone born at the 9th vs. 11th percentile.
Secondly, we wanted to determine if there was a point when birthweight percentiles could get too large (i.e is there a Goldilocks effect, maybe you should not be too small but not too big either)

MedicalResearch.com: What are the main findings? Is there a cutoff level at which the findings plateau, ie over 7 pounds or after 38 weeks?

Response:  So we find that increasing birthweight percentiles are associated with improved cognitive development, from the 1st percentile until the 69th birthweight percentile, where cognitive scores plateau but do not subsequently reduce. To put this into perspective, if we imagine two 40-week infants, a male infant born at 8lbs, 10oz (3913g) and a female infant born at 8lb, 5oz (3770g), they are both born at the 69th birthweight percentile relative to their sex and week of gestation. Thus our results indicate that as the relative birth weight gets lower and lower, the chance of reduced cognitive performance gets greater and greater.

However, we did not find evidence that being a relatively large baby is associated with lower cognitive performance, which we thought was a somewhat surprising finding.

MedicalResearch.com: What should readers take away from your report?

Response: First of all, it is important to emphasize that these are average scores for infants of differing birthweight percentiles. As such, there will be many infants who have very low birthweight percentiles but go on to have perfectly normal cognitive development and perform exceptionally well in school and later life. However, we would indicate that if we would like to identify infants who may need more help later in life, knowing the gestational age and the birthweight percentile may allow us to perform earlier, more targeted interventions.

MedicalResearch.com: What recommendations do you have for future research as a results of this study?

Response: One area that we are looking to investigate further is how birthweight and parenting factors interact for later cognitive development. Research has indicated that factors such as stimulating and sensitive parenting are associated with improved cognitive outcomes.

However, are parenting factors particularly important for lower birthweight infants? I.e are lower birthweight infants more sensitive to the influence of parenting relative to normal birthweight infants?  In sum, we hope to identify why some infants appear particularly resilient despite being born at risk, and whether specific parenting or environmental factors can help to explain this.

MedicalResearch.com: Is there anything else you would like to add? Any disclosures?

Response: A huge thank you should be said to all the researchers, parents, and participants who allow for these types of long-term investigations to take place. Without the dedicated support of all of these groups, research like this would not be possible.

I have nothing to disclose.


Eves RWolke DSpiegler JLemola S. Association of Birth Weight Centiles and Gestational Age With Cognitive Performance at Age 5 Years. JAMA Netw Open. 2023;6(8):e2331815. doi:10.1001/jamanetworkopen.2023.31815

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Last Updated on September 3, 2023 by Marie Benz