Regnerus added that while these kinds of sample selection bias and challenges in collecting data are difficult to avoid in studies, particularly on a subject like abortion, they do introduce unknowns into the study.
"I don't think porn use necessarily causes that, but contributes to it (together with diminished earnings power, diminished confidence, etc.)," he added. "To be sure, porn use doesn't help build confidence in men, something that's pretty necessary (but not sufficient) to be considered marriageable. So I'd say porn use is a suspect here, but connecting the dots is hardly straightforward."