From ‘Covid-19: Children born during the pandemic score lower on cognitive tests, study finds’, published in BMJ:
“Children born during the pandemic score markedly lower on standard measures of verbal, motor, and overall cognitive ability, US researchers have found. In a longitudinal study of 672 children from Rhode Island that has run since 2011, those born after the pandemic began showed results on the Mullen scales of early learning that corresponded to an average IQ score of 78, a drop of 22 points from the average of previous cohorts.”
Lead author, Sean Deoni of Brown University, said, “the closest thing we’ve seen in other research—and this is horrible, not a good comparison to be making—is the studies that were done of orphans in Romania. The effects of institutionalisation and lack of interaction on them were profound, but what we’re seeing here is on par with that.”
The authors noted children born in 2019 did not experience a decline in development scores during the pandemic. Babies from low-income families were most impacted, and boys were more affected than girls.
Mothers and children with a history of testing positive for SARSCOV2 were excluded from the analysis.
Another group of researchers at Columbia University found in a different study that, “both exposed and unexposed infants born during that period had significantly lower scores on gross motor, fine motor, and personal-social subdomains compared with a historical cohort of infants born before the onset of the COVID-19 pandemic.”
“…the authors (of the Brown University study) say, reduced interaction with parents and less outdoor exercise are likely culprits, along with effects that occurred during pregnancy.”
A New Hypothesis: Vitamin D
Some studies have been done assessing the association between vitamin D status during pregnancy and infant neurodevelopment (cognitive, language, and motor skills).
“Vitamin D status during pregnancy is involved in numerous physiological processes, including brain development. … This prospective longitudinal study of a large sample of pregnant women with no previous pathology has shown that the women’s vitamin D levels at the beginning and end of gestation had significant effects on the neurodevelopment of their children at 40 days. … Regardless of other associated factors, deficient vitamin D levels in the first trimester of pregnancy predicted worse performance in cognitive and language skills. Language performance especially was significantly lower when vitamin D levels were highly deficient (<20 nmol/L). During the third trimester, this highly deficient vitamin D level also affected motor development.”
“Second-trimester maternal 25(OH)D was positively associated with IQ at 4–6 y, suggesting that gestational vitamin D status may be an important predictor of neurocognitive development.”
Impact on Low-Income Babies
An explanation for why the cognitive effects were higher in low-income babies could be their outdoor time relies on the use of shared public spaces which were often closed (or avoided in honor of social distancing) during the pandemic.
Male vs Female
One possible explanation for seeing increased effects in males compared to females could be estrogen levels. When Rhonda Patrick, PhD, attempted to find a possible mechanism which could explain links between vitamin D status and autism, she noted (in ‘Vitamin D hormone regulates serotonin synthesis. Part 1: relevance for autism’) higher estrogen levels in females could affect the impact of low Vitamin D on development.
Vitamin D During Pandemic
I wasn’t able to find studies measuring vitamin D levels in pregnant women during the pandemic (compared to pre-pandemic), but I did find ‘How Vitamin D Levels of Children Changed During COVID-19 Pandemic: A Comparison of Pre-pandemic and Pandemic Periods’, which concluded,
“Pandemic-related restrictions have caused significant decreases in vitamin D levels of school-aged children and adolescents.”
Further investigation is needed.