Pain from illnesses such as cancer, pheochromocytoma, complex regional pain syndrome, or sickle cell disease can manifest during pregnancy or present as a preexisting condition.

Analgesic rules during pregnancy:
- All opioids and non-opioid analgesics can pose known or unknown risks to the fetus.
- Generally, most analgesics pose less risk to the fetus in the first trimester.
- From the late 2nd trimester and onward, increased risk is associated with aspirin due to bleeding concerns; NSAIDs due to premature closure of ductus arteriosus; and opioids (broadly, they should be avoided throughout pregnancy, unless they are necessary to treat acute pain or addiction).

Counseling bottom line:
Changes in physiology of the woman and fetus throughout pregnancy affect the maternal and fetal bioavailability of opioids and require ongoing dose adjustments when opioids are prescribed.
Although there is limited evidence, it is necessary to remember the following:
- Avoid codeine, oxycodone, and hydrocodone due to a potential increased risk of birth defects.
- Morphine, fentanyl, or hydromorphone may be the opioids of choice for pain; methadone or buprenorphine for opioid addiction; and fentanyl for breastfeeding mothers.
- Opioid use longer than a few weeks may result in neonatal abstinence syndrome and should be instituted with caution.

See reference for more information.

Adapted from Malotte KL, Hirsch, Groninger H. Palliative Care Network of Wisconsin. Fast facts and concepts #344. Opioids for serious illness during pregnancy. Internet. Accessed on January 4, 2018.