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In-utero exposure to bereavement and offspring IQ: a Danish national cohort study.

ABSTRACT: BACKGROUND: Intelligence is a life-long trait that has strong influences on lifestyle, adult morbidity and life expectancy. Hence, lower cognitive abilities are therefore of public health interest. Our primary aim was to examine if prenatal bereavement measured as exposure to death of a close family member is associated with the intelligence quotient (IQ) scores at 18-years of age of adult Danish males completing a military cognitive screening examination. METHODS: We extracted records for the Danish military screening test and found kinship links with biological parents, siblings, and maternal grandparents using the Danish Civil Registration System (N = 167,900). The prenatal exposure period was defined as 12 months before conception until birth of the child. We categorized children as exposed in utero to severe stress (bereavement) during prenatal life if their mothers lost an elder child, husband, parent or sibling during the prenatal period; the remaining children were included in the unexposed cohort. Mean score estimates were adjusted for maternal and paternal age at birth, residence, income, maternal education, gestational age at birth and birth weight. RESULTS: When exposure was due to death of a father the offsprings' mean IQ scores were lower among men completing the military recruitment exam compared to their unexposed counterparts, adjusted difference of 6.5 standard IQ points (p-value = 0.01). We did not observe a clinically significant association between exposure to prenatal maternal bereavement caused by death of a sibling, maternal uncle/aunt or maternal grandparent even after stratifying deaths only due to traumatic events. CONCLUSION: We found maternal bereavement to be adversely associated with IQ in male offspring, which could be related to prenatal stress exposure though more likely is due to changes in family conditions after death of the father. This finding supports other literature on maternal adversity during fetal life and cognitive development in the offspring.

SUBMITTER: Virk J

PROVIDER: S-EPMC3928249 | biostudies-other | 2014

REPOSITORIES: biostudies-other

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Project description:The aim of this study was to assess the risk of injuries among children exposed to a stressful life exposure (defined as bereavement) before conception or during fetal life.Population-based cohort study.Denmark.All singleton births in Denmark between 1 January 1995 and 31 December 2006 were identified. These newborns were then linked to mothers, fathers, grandparents and siblings using individually assigned civil personal registration numbers.We identified that data on childhood injuries were obtained from the Danish National Patient Registry, which contains data on all hospital stays and outpatient visits. Incidence rate ratios (IRRs) were estimated from birth using log-linear Poisson regression models, and person-years were used as the offset variable. Age, residence, calendar period, maternal education, maternal income and parental-cohabitation status are treated as time-dependent variables (records were extracted from the offspring's birth year).Exposure to maternal bereavement due to a father's death had the strongest association with childhood injuries, especially when the cause of death was due to a traumatic event (adjusted estimates of IRR (aIRR): 1.25, 95%CI: 0.99 to 1.58). We did not find an association for childhood injuries and maternal bereavement due to grandparent's death, and we only found an association for sibling death when restricting to deaths due to traumatic events (aIRR: 1.20, 95%CI:1.03 to 1.39).The aetiology of childhood injuries is complex and may be related to events that take place during prenatal life. This study suggests that exposure to a stressful life event during gestation may be linked to injury susceptibility in childhood. However, changes in postnatal family conditions related to loss or genetic factors may also play a role.Developmental plasticity related to early life exposures leading to disease programming in offspring is a theory with substantial theoretical and empirical support. Prenatal stress exposure has been linked to neurological outcomes, such as temperament, behavioural problems, cognitive function and affective disorders. If exposure modifies risk-seeking behaviour, perceived danger and reaction time, it is also expected to modify injury risk.

Project description:BackgroundPrenatal exposures to phthalates and bisphenols are associated with impaired brain development in animals. However, epidemiological studies investigating the association between prenatal phthalate or bisphenol exposure and cognition have produced mixed findings and mostly had modest sample sizes and measured the exposure during the third trimester.ObjectiveWe examined the association between pregnancy maternal urinary biomarkers of phthalate or bisphenol exposure and nonverbal intelligence quotient (IQ) in children 6 years of age.MethodThe study sample consisted of 1,282 mother-child pairs participating in the Generation R Study, a population-based birth cohort in Rotterdam, Netherlands (enrollment 2002-2006). We measured maternal urinary concentrations of 18 phthalate metabolites and 8 bisphenols at <18, 18-25, and >25 wks of gestation. Child nonverbal IQ was measured at 6 years of age using the Snijders-Oomen Nonverbal Intelligence Test-Revised. Linear regression models were fit for each of the three collection phases separately, the three collection phases jointly, and for the averaged prenatal exposure across pregnancy.ResultsHigher urinary concentrations of phthalate metabolites during early pregnancy were associated with lower child nonverbal IQ score [e.g., B per 10-fold increase in summed low-molecular weight phthalates=-1.7 (95% CI: -3.1, -0.3)]. This association remained unchanged when adjusted for mid and late pregnancy exposures. We also observed an inverse association between late pregnancy di-n-octyl phthalate (DNOP) exposure and nonverbal IQ. Maternal urinary concentrations of bisphenols were not associated with child nonverbal IQ. There was no effect estimate modification by sex.ConclusionsWe did not observe that maternal biomarkers of bisphenol exposure are associated with nonverbal IQ. We found that phthalate exposure in early pregnancy and DNOP exposure in late pregnancy are associated with lower nonverbal IQ scores in children. Our results might suggest that particularly early pregnancy is a sensitive window of phthalate exposure, but future studies are needed to replicate our findings. https://doi.org/10.1289/EHP6047.

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In-utero exposure to bereavement and offspring IQ: a Danish national cohort study.

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