Analgesics are taken for a short period of time, usually 2 or 3 days. Acetaminophen, with a pregnancy risk category B, is the safest drug for management of short-term oral pain during pregnancy. However, there is a potential for liver toxicity in higher dosages. As it is an over-the-counter drug and patients may not read the accompanying directions and precautions, patients should receive detailed instructions from the health professional on how long to take the drug and the maximum daily dose (no more than 4g/day for adults).
Aspirin is classified in category C until the third trimester when it is considered a category D drug due to its inhibition of prostoglandin synthesis, which may result in delivery complications, premature closure of the fetal ductus arteriosis and antepartum/postpartum maternal/fetal hemorrhage. High doses may be related to increased perinatal mortality, intrauterine growth retardation and teratognic effects; while chronic use may cause anemia in the mother. During breastfeeding, aspirin can interfere with the infants platelet function.
Ibuprofen and naproxen are category B drugs in the first and second trimesters, but a category D in the third trimester because of association with lower levels of amniotic fluid, premature closure of the fetal ductus arteriosis and inhibition of labor if taken during that time. Ibuprofen is considered safe during breastfeeding.
The obstetrician should be consulted prior to prescription of more potent drugs for severe pain. When greater pain control is required, obstetricians often prescribe a combination of acetaminophen and codeine (Tylenol #3) in lieu of nonsteroidal anti-inflammatory drugs (NSAIDS). However, there is a possible association between codeine use and multiple congenital defects including heart and circulatory defects and cleft lip and palate. Additionally, prolonged use of narcotics in the third trimester can result in neonatal respiratory depression. There is concern about the use of codeine by nursing mothers as codeine is more rapidly metabolized into morphine, which can be passed along to the breast fed infant. Mothers taking codeine should contact their physician if the infant exhibits increased signs of sleepiness (more than 4 hours at a time), limpness and difficulty with nursing or breathing.
Combinations of acetaminophen and hydrocodone (Vicodin) are classified as category C unless taken in high doses at term or chronically, at which time they are classified as a category D drug. Other opioid drugs such as Percodan, Vicoprofen, Empirin, Talwin, Darvocet and Demerol should be avoided.