Use of Analgesia in Pregnancy

• Because of fear about use of drugs during pregnancy, some pregnant women would rather suffer than treat their pain. 
• Chronic, severe pain that is ineffectively treated is associated with hypertension, anxiety, and depression—none of which is conducive to a healthy pregnancy

Summary of Recommendations:

• recommend paracetamol as first-line treatment of fever and pain during pregnancy. 
• Codeine or another opioid analgesic can be added to treat more severe pain. 
• NSAID use is contraindicated in the third trimester and alternative analgesics should also be considered in the first trimester.
• Women and their doctors should however be reassured that there are safe options to treat pain, both acute and chronic, during pregnancy and breastfeeding

Acetaminophen

• efficacy and apparent safety at all stages of 
• recent study of thousands of pregnant women showed it does not increase risks of congenital anomalies or other adverse pregnancy outcomes
• weight of evidence is inconclusive regarding a possible connection between acetaminophen use in pregnancy and ADHD in children (FDA)

Aspirin

• Aspirin has potential risks, as it inhibits platelet function and can contribute to maternal and fetal bleeding.
• Although aspirin has not been associated with other congenital anomalies, it has been associated with increased risk of vascular disruption, in particular gastroschisis, although this remains unproven.
• Overall, large trials demonstrate low-dose aspirin’s relative safety and generally positive effects on reproductive outcomes

NSAIDS

• To date, studies have failed to show consistent evidence of increased teratogenic effects in either humans or animals following therapeutic doses during the first trimester. 
• weight of evidence is inconclusive regarding a possible connection between NSAID use and miscarriage (FDA)
• However, even short-term use of NSAIDs in late pregnancy is associated with a substantial increase in the risk of premature ductal closure
• main concerns with the COX-2 inhibitors are effects on the ductus arteriosus as well as perfusion of the fetal/neonatal kidney and intestine. 
• Topical NSAIDs generally result in negligible blood levels and would be considered to be relatively safe in pregnancy although absorption is increased by use over a large surface area or the application of heat

Opioids

• These agents include morphine-like agonists (eg, morphine, hydromorphone, hydrocodone, codeine, and oxycodone), meperidine-like agonists, and synthetic opioid analogues (eg, tramadol). 
• Reproductive studies describing the use of narcotic analgesics in human pregnancies are limited, and there are no prospective, comparative studies. 
• However, these drugs have been used in therapeutic doses by pregnant women for many years and have not been linked to elevated risk of major or minor malformations.
• The main concern about these drugs is that persistent use may lead to dependence and tolerance in the mother with resultant withdrawal (neonatal abstinence syndrome) in the neonate
• Further investigation is needed before we can determine whether the weight of evidence supports the presence of an increased risk of neural tube defects related to opioid exposure in early pregnancy
• Neonatal withdrawal has been observed with use of codeine in late pregnancy, even with therapeutic doses in nonaddicted mothers
• Sometimes alternative drugs including tricyclic antidepressants may help to control persistent pain and reduce opioid exposure. Tricyclic antidepressants have not been associated with an increased rate of birth defects or long-term neurodevelopmental effects

Fentanyl patch

• without reports of serious adverse effects, and it is considered effective for all types of chronic pain, including cancer and non-cancer pain.
• There is little information on its use in pregnancy, with only 2 case reports in the literature. 
• In one, a high-dose fentanyl patch (ie, 125 μg/h) was used throughout pregnancy, and the newborn infant manifested mild withdrawal symptoms at 24 to 72 hours after birth.
• In the other, which was from the Motherisk team, a lower dose of the fentanyl patch was used with no apparent adverse effects

References:
http://www.australianprescriber.com/magazine/34/1/8/10
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2809170/
http://www.fda.gov/Drugs/DrugSafety/ucm429117.htm