title: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: UCLA/Fielding School of Public Health, Department of Epidemiology, University of California Los Angeles, Los Angeles, California, United States of America.
authors.forename: Jasveer
authors.initials: J
authors.lastname: Virk
authors.affiliation: Section for General practice, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Obel
authors.affiliation: Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: Jiong
authors.initials: J
authors.lastname: Li
authors.affiliation: Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
mesh_terms: D000293:Adolescent; D001601:Bereavement; D001724:Birth Weight; D003071:Cognition; D015331:Cohort Studies; D003718:Denmark; D005220:Fathers; D005260:Female; D006117:Grief; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D009035:Mothers; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D035781:Siblings