Siranda Torvaldsen of the University of Sydney, Australia, found that 416 women given the opioid drug fentanyl by
epidural injection during delivery were twice as likely to have stopped breastfeeding their baby by the age of six months compared with 312 women who didn't
receive epidural fentanyl (International Breastfeeding Journal, DOI: 10.1186 / 1746 -4358-1-24).