In the DrugsInPregnancy project, we have linked epidemiological data from the birth cohort and national registries. Cord blood samples for a pharmacoepigenetic study on paracetamol have been analysed. We have performed studies specifically assessing different aspects of data quality and availability of advanced methods for confounding control within reproductive pharmacoepidemiology. Our work has raised important debates on how child neurodevelopmental disorders and delays should be detected, and how DNA-methylation analysis using cord blood should be correctly performed. We advocate that use of advanced methods for confounding control, handling of missing data, use of longitudinal methods for modelling medication exposures and methods for adjusting for time-varying confounders will enable improved causal inference about effects of prenatal exposure to medications on human neurodevelopment. We argue that psychometric instruments and diagnoses of developmental disorders have different strengths and weaknesses and will supplement each other, and that without correction for cell type composition in studies on DNA-methylation erroneous conclusions will be made.
In this project, we found no substantial increased risk for ADHD diagnosis, externalizing, emotional, or social problems in preschool-aged children following prenatal SSRI-antidepressant exposure, beyond that posed of the maternal underlying illness. We found a slightly elevated risk of ADHD diagnosis after exposure to opioids for 5 or more weeks during fetal life. Taken together, the results from several studies on benzodiazepines and/or z-hypnotics were reassuring. Our findings suggested no increased risk of ADHD diagnosis, child fine motor problems, externalizing and internalizing problems at 5 years of age after prenatal exposure to benzodiazepines and/or z-hypnotics. Residual confounding by indication and/or a higher drug dose regimen among women with anxiety/depression may explain a moderate association of gross motor and communication deficits with late-pregnancy benzodiazepine/z-hypnotic use.
We have found that prenatal exposure to low doses paracetamol is associated with reduced risk of ADHD, whereas high doses increases risk of ADHD in offspring. We have demonstrated that there may be a link between use of high doses paracetamol among children with ADHD and altered DNA-methylation patterns.