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Association of prenatal stress due to maternal bereavement with intellectual disability in the offspring.

OBJECTIVE
To examine the association of mother's loss of a close relative before or during pregnancy with intellectual disability (ID) in the offspring.


METHODS
We performed a nationwide population-based cohort study based on Danish national registries. All live-born singletons born in Denmark during 1978-2016 (n = 2,) were followed started from birth until up to 38 years of age. Log-linear Poisson Regression was used to estimate the association between maternal bereavement (the death of an older child, a partner, or a parent one year before or during pregnancy) and the risk of ID in the offspring.


RESULTS
Maternal bereavement during or before pregnancy was associated with an increased risk of ID (IRR = 1.15; 95%CI 1.04-1.28). The risk of ID was increased by 27% when maternal bereavement occurred during pregnancy (IRR = 1.27; 95%CI 1.08-1.49). When stratifying on the child's sex, we also observed an increased risk of ID associated with maternal bereavement during pregnancy both for male (IRR = 1.25; 95%CI 1.02-1.53) and for female (IRR = 1.31; 95%CI 1.02-1.69), respectively. The IRRs for unnatural death of a relative were also elevated (IRR = 1.22; 95%CI 0.91-1.64) in general, although the difference was not statistically significant.


CONCLUSIONS
Our findings suggest that prenatal stress due to maternal loss of a close relative may increase the risk of offspring's ID of both sexes, in particular when the loss happened during pregnancy.