Paternal exposure to recreational drugs before conception and its effect on live-born offspring A scoping review.
Men of reproductive age increasingly use recreational drugs. While many of these substances may reduce the quantity and quality of sperm, less is known about the effects of these exposures on their offspring. We performed a scoping review to summarize the available literature and identify areas for future research on the outcome of live-born offspring of fathers who were exposed to recreational drugs before conception. A systematic search was conducted of the Medline, EMBASE, and Web of Science databases, which included keywords for the following substances cannabis-related products, cocaine, heroin, hallucinogens, ecstasy and amphetamines. In total, 2,983 records were screened, and 129 publications were selected for full-text assessment. Publications were included if (a) the timing of exposure included the preconceptional period, and (b) if outcomes in live-born offspring were compared with an unexposed group. We included 30 publications, of which 15 animal studies and 15 human studies. Animal studies showed neurocognitive abnormalities, in particular in male offspring. Interestingly, these outcomes depend significantly on the method of exposure (i.e., fixed-dose administration vs. variable self-administration, which mimics addiction). Human studies were limited to specific congenital malformations and childhood cancers, which showed small increased odds ratios. While animal studies describe impaired neurocognitive outcomes following paternal exposure to recreational drugs, data in humans is currently lacking. Human studies require sound methodology in order to confirm findings on congenital malformations and childhood cancers. In addition, future neurocognitive studies require parental neurocognitive assessments to correct for confounding effects (i.e., role of genetics).