Individuals who are pregnant or breastfeeding are advised against testosterone therapy as part of gender affirming care due to potential risks to both the individual and the developing fetus or breastfeeding infant. Testosterone, a key component of masculinising hormone therapy, can cross the placental barrier during pregnancy or transfer to the infant through breast milk during lactation. Exposure to testosterone during pregnancy may lead to virilisation of female fetuses, resulting in potential masculinisation of external genitalia or other developmental abnormalities. Similarly, testosterone exposure through breastfeeding may pose risks to the infant’s health and development. Therefore, individuals who are pregnant or breastfeeding must stop testosterone therapy until after pregnancy and breastfeeding are completed.
