Maternal factors linked to neonatal brain structure

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According to a recent study published in JAMA Network Open, low birth gestational age (GA) and socioeconomic status (SES) are associated with neonatal brain structure.

About 11% of births worldwide are preterm, defined as under 37 weeks of gestation. This is associated with atypical brain development, leading to long-term cognitive, motor, and behavioral outcomes. GA has been linked to adverse outcome risks, with infants born under 28 weeks’ gestation at the greatest risk.

Childhood SES has also been linked to cognitive outcomes in the general population. Childhood poverty has been associated with memory, self-regulation, language, and socioemotional processing issues.

Understanding the impact of GA and SES on neonatal brain development is vital for developing strategies to support children in these populations. To evaluate the association between GA and SES with neonatal brain structure, investigators conducted a longitudinal study using high-resolution brain magnetic resonance imaging (MRI) from infants.

Participants included extreme or very preterm infants, defined as under 33 weeks of gestation, and full-term or near-term infants. Recruitment occurred from November 2016 to September 2021 at the Royal Infirmary of Edinburgh, United Kingdom.

Infants with hemorrhagic parenchymal infarction, chromosomal abnormality, congenital infection, congenital malformation, cystic periventricular leukomalacia,posthemorrhagic ventricular dilatation, and significant parenchymal brain injury were excluded from the analysis.

GA categories included 22 weeks, 0 days, to 26 weeks, 6 days; 27 weeks, 0 days, to 28 weeks, 6 days; 29 weeks, 0 days, to 30 weeks, 6 days; and 31 weeks, 0 days, to 32 weeks, 6 days. SES was measured by neighborhood-level, family-level, and subjective SES based on self-report.

Additional SES measures included maternal and paternal education and occupation. Ethnicity data was also gathered because of a connection between ethnicity and SES. Covariates included birth weight z score, infant sex, birth head circumference z score, age at MRI, breast milk at discharge, and smoking in pregnancy.

MRI scans were,“performed at term-corrected gestation according to a published protocol,” with infants continuously watched. Trained doctors and nurses monitored scans. A radiologist experienced in neonatal MRI was consulted to report structural images. 

There were 85 individual region brain parcels and 5 whole-cortex measures evaluated for associations of SES and GA with lobar regional volumes, lobar cortical measures, and whole brain volume.

Of participants, 170 were extremely or very preterm, while 91 were full-term or near-term. Ethnicity and sex distribution did not display significant differences between groups. However, differences were observed in multiple pregnancy, smoking prevalence, and SES measures.

The Scottish Index of Multiple Deprivation 2016 (SIMD) was used to define neighborhood-level SES and was not as significantly associated with regional brain volumes as GA at birth. Of the 85 parcels examined, GA was associated with the volume of 26%, while SIMD was associated with 1.2%. 

GA was negatively associated with cerebrospinal fluid spacevolume but did not directly interact with SIMD in any brain region. When evaluating associations with cortical morphology, SIMD had no associations while GA was associated with cortical surface area.

While more associations were found between GA and brain volume, multiple associations were also found between SES and brain volume. Four parcels were impacted by maternal education level, 1 by neighborhood SES, and 1 by maternal occupation. A positive association between family-level SES and regional tissue volume was reported.

GA-volume associations were reported in 25.9% of parcels for paternal education, 24.7% for paternal occupation, 17.6% for maternal education, and 14.1% for maternal occupation. Associations for subjective SES were found in 20% of parcels.

Overall, associations with neonatal brain structure were found for both GA and SES. Investigators recommended further research on the biological mechanisms associated with preterm birth and brain development.

Reference

Mckinnon K, Galdi P, Blesa-Cábez M, et al. Association of preterm birth and socioeconomic status with neonatal brain structure. JAMA Netw Open. 2023;6(5):e2316067. doi:10.1001/jamanetworkopen.2023.16067