Depression during pregnancy can affect an unborn child’s brain
Scientists report that babies born to mothers who experienced lots of stress (depression) during pregnancy tend to have problems with brain development, which may affect their behaviours when they grow up. If healthcare workers are able to identify depressed pregnant persons, they could provide them with help to limit negative effects on their unborn babies.
In South Africa, studies show that about half of pregnant women experience depression. Researchers say that these stressful pregnancies might be the cause of negative behaviours in children born to these mothers when they grow into adults.
In this study, the researchers investigated how depression during pregnancy can specifically affect brain development of the unborn child.
They studied pregnant women aged above 18 years, who were between 3 and 6 months pregnant. The women had their health check-ups in South Africa. They assessed them for signs of depression, and checked if they were consuming any alcohol or drugs to suppress their emotions.
The researchers followed-up with the women again after they delivered their babies, and took detailed pictures, or brain scans, of their babies’ brains when they were 2-4 weeks old, and again at 2–3 years.
The researchers split the women into 2 groups: those who were depressed and those who were not.
They reported that children’s weights in both groups were similar at each time point. However, at 2-3 weeks, children born to depressed women had smaller heads and were shorter than those born to non-depressed women.
The researchers also said women who were depressed tended to drink alcohol and smoked tobacco more than those who did not have stress.
When the doctors analysed the children’s brain scans, they did not find any difference between the 2 groups at 2-3 weeks. However, after 2-3 years, researchers found that brains of children born to stressed women were not well connected and had been affected. The connections between brain cells, or neurons, can be a measure of intelligence, language ability and memory, so children with brains that are not well connected may have problems in these areas.
The researchers said they found that the part of the child’s brain called the ‘sagittal stratum’, was most affected when the child’s mother was stressed during pregnancy. ‘Sagittal stratum’ is the front part of the brain and has many fibres. Fibres are long and thin thread-like structures of the brain.
The researchers said their study was the first to give evidence of how depression in pregnant women could affect the brains of their children.
They however said some other factors which they did not measure might have affected the babies’ brain development or their behaviour at a later stage. They also said they could not follow-up all the children after birth, especially at 2-3 years.
The study was done in South Africa, by researchers based in universities in South Africa and the United States of America.
Prenatal exposure to maternal depression increases the risk for onset of emotional and behavioral disorders in children. Here, we investigated the effects of exposure to prenatal depression on white matter microstructural integrity at birth and at 2–3 years, and associated neurodevelopment. Diffusion-weighted images were acquired for children of the Drakenstein Child Health Study at 2–4 weeks postpartum (n = 70, 47% boys) and at 2–3 years of age (n = 60, 58% boys). Tract-Based Spatial Statistics was used to compare diffusion tensor metrics across groups defined by presence (> 19 on Beck’s Depression Inventory and/or > 12 on the Edinburgh Postnatal Depression Scale) or absence (below depression thresholds) of depression, and associations with neurodevelopmental measures at age 2–3 years were determined. We did not detect group differences in white matter integrity at neonatal age in this cohort, but at 2–3 years, children in the exposed group demonstrated higher fractional anisotropy, and lower mean and radial diffusivity in association tracts compared to control children. This was notable in the sagittal stratum (radial diffusivity: p < 0.01). Altered white matter integrity metrics were also observed in projection tracts, including the corona radiata, which were associated with cognitive and motor outcomes in exposed 2-3-year-olds (p < 0.05). Our findings of widespread white matter alterations in 2-3-year-old children with prenatal exposure to depression are consistent with previous findings, as well as with neuroimaging findings in adults with major depression. Further, we identified novel associations of altered white matter integrity with cognitive development in depression-exposed children, suggesting that these neuroimaging findings may have an early functional impact.
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