Background. Maternal prenatal depression is a known risk factor for early-life psychopathology among offspring. However, it is necessary to distinguish between potential mechanisms by which this risk may be transmitted to properly understand the clinical and epidemiological implications of this link.
Objective. To test the relative importance of passive genetic transmission, direct exposure, and indirect exposure in the association between maternal prenatal depression and later internalizing and externalizing psychopathology.
Design. Structural equation modelling of phenotypic data and genetically-informative relationships the families of participants in the Norwegian Mother and Child Birth Cohort Study (MoBa). Setting. The MoBa sample was recruited at routine ultrasound examinations offered to all pregnant women in Norway, between July 1999 and December 2008.
Participants. The total MoBa sample includes >114,500 children, >95,000 mothers, and >75,000 fathers. The analytic sub-sample of MoBa used in the current study comprises 33,580 mothers and 27,459 children.
Main outcomes and measures. We used mothers’ self-reported depressive symptoms during pregnancy, as captured by the Symptom Checklist (SCL), and their reports of symptoms of psychopathology in their offspring during the first few years of life (measured at 18, 36 and 60 months using the Child Behavior Checklist [CBCL]).
Results. Maternal prenatal depression was found to be associated with both internalizing and externalizing problems in early childhood primarily via intergenerationally-shared genetic factors. For internalizing problems, phenotypic transmission also contributed significantly to the association, but was found to be explained by exposure to concurrent maternal depression, rather than by direct exposure.
Conclusions and relevance. Associations between maternal prenatal depression and offspring behavioral outcomes in early childhood are likely to be at least partially explained by shared genes. This genetic confounding should be considered when attempting to quantify risks posed by in utero exposure to maternal depression.
