It is excreted in breast milk in very small quantities (Al-Tamimi 2011, Borgatta 1997, Quinn 1986, Peiker 1980) and, in general, no problems have been observed in infants whose mothers were taking it (Al-Tamimi 2011). After a caesarean section, newborns whose mothers were treated with pethidine to relieve pain showed greater signs of neurological depression during the first three days than those whose mothers were treated with morphine (Reynolds 2011, Wittels 1997 and 1990). Newborns whose mothers received pethidine, compared to mothers who received fentanyl, morphine or no analgesic drug, had more problems establishing breastfeeding in the first few days, less initial frequency of breastfeeding or greater early stopping of breastfeeding (Fleet 2016 and 2015, Wilson 2010, Yost 2004, Torvaldsen 2006, Ransjö 2001, Spigset 2000, Nissen 1997 and 1995, Lee 1993). The elimination of the metabolite norpethidine is slower, with a T½ of 20 hours (Lee 1993, Quinn 1986).Due to these considerations, although the American Academy of Pediatrics considered it to be a medication which was usually compatible with breastfeeding (AAP 2001), later it advised against its use (Sachs 2013) together with other scientific organizations (ABM Protocol # 15 2017 and 2012, ASGE 2012, Gastroenterology, 2012). Isolated doses for short procedures are unlikely to affect the infant (ABM Protocol # 15 2017 and 2012, WHO / UNICEF 2002).Avoid repeated doses. Monitor sedation and weak suction, especially in the neonatal period (WHO / UNICEF 2002).