Hydromorphone has not been adequately studied in pregnant women to determine whether it is effective and safe. Because low quantities of opioid medicines can pass into breast milk, they should not be taken by nursing mothers. Morphine injections must only be given in pregnancy when no other options for pain relief are available and the fetus can be monitored. Chronic dosing may cause unwanted side effects or symptoms of withdrawal in newborns. Although morphine is secreted in breast milk, an American Academy of Pediatrics committee has determined that using it during nursing is safe.