Prolonged exposure to acetaminophen during pregnancy may suppress testosterone production by fetal testes, according to a study conducted by investigators from the University of Edinburg, United Kingdom, that used a xenograft model in which human fetal testes were transplanted into castrated mice (van den Driesche S et al. Sci Transl Med. 2015;7:288ra80).
In mice grafted with human fetal testes that were treated with a human-relevant dose of acetaminophen (20 mg/kg) 3 times a day for 1 week, testosterone levels in the blood decreased by 45%, and weight of the seminal vesicle glands, a biomarker of testosterone exposure, fell by 18%. Acetaminophen treatment for a single day had no effect on testosterone production.
Hampton T. Acetaminophen During Pregnancy May Affect Offspring’s Testes. JAMA. 2015;314(1):16. doi:10.1001/jama.2015.7177