More than 14 percent of pregnant women prescribed opioids, study says

More than 14 percent of pregnant women were prescribed opioids (narcotics) for pain at some time during their pregnancy, according to a study posted to the online version of Anesthesiology.  Given the surprising rate these medications were prescribed to pregnant women, more research is needed to assess the risk of opioids to unborn babies, the study suggests.

Prescriptions for opioids increased almost threefold in the general population, to more than 200 million between 1991 and 2009, according to the National Institutes of Health.  This study found the prevalence of opioid use by pregnant women in the U.S. is significantly higher than in Europe. The rate of opioid use also varied throughout the country with the highest in the South and lowest in the Northeast. 

“Nearly all women experience some pain during pregnancy,” said Brian Bateman, M.D., M.Sc., assistant professor, Harvard Medical School, and study author. “However, the safety of using opioids to manage their pain remains unclear. Ultimately, we need more data to assess the risk/benefit ratio of prescribing these drugs to women and how it may affect their babies.”

The study looked at data from a research database of more than 530,000 pregnant women enrolled in a commercial insurance plan who delivered their babies between 2005 and 2011. Their median age was 31. The study investigated which opioids were most often prescribed, what pain was most frequently treated and how the prevalence varied regionally.

Of the more than 530,000 pregnant women, 76,742, or 14.4 percent, were prescribed opioids at some point in their pregnancy.  Most opioid exposures were for short courses of treatment, usually less than a week. The percentage of women dispensed an opioid in the first and second trimester was 5.7; in the third trimester it was 6.5 percent.  Of these women, 2.2 percent were dispensed opioids three or more times during pregnancy. 

Back pain was the most common condition (37 percent) for which opioids were prescribed, according to the study. Other conditions included abdominal pain, migraine, joint pain and fibromyalgia. The most commonly prescribed opioid during pregnancy was hydrocodone (6.8 percent), followed by codeine (6.1 percent), oxycodone (2.0 percent) and propoxyphene (1.6 percent).  Prescription patterns varied regionally, according to the study.  Opioid use ranged between 6.5 percent and 26.3 percent, with the lowest rate in the Northeast and highest in the South. Arkansas, Mississippi and Alabama all had prescription rates in excess of 20 percent.

In a commentary on the study, Pamela Flood, M.D., professor of anesthesiology, Pain and Perioperative Medicine at Stanford University, Stanford, Calif., notes that “the risk to the fetus of short-term exposure to prescription opioids under medical supervision is difficult to assess and needs to be carefully examined in future studies.”

She explains that previous studies have had contradictory findings regarding the risk to the baby. An early U.S. study (1959-1965), and later studies from Sweden and Norway, did not find an association between opioid prescription and birth defects. However, a U.S. National Birth Defects Prevention Study (1997-2005) found associations between codeine and other opioids with birth defects, including atrial and ventricular septal defects, hypoplastic left heart syndrome, spina bifida and gastroschisis in newborns. Additionally, the U.S. national study cites that when opioids are used long-term during pregnancy, “there is a known risk for neonatal opioid dependence and subsequent withdrawal symptoms in the first few days of life.”

“Pain occurring at some time during the course of pregnancy is common,” said Edward A. Yaghmour, M.D., chair, ASA Committee on Obstetric Anesthesia. “We need to carefully balance medications given to the mother and the risk to her and her baby. For example, we would never stop giving anti-seizure medication or medication for diabetes; the danger in those situations is clear. With opioids, there are simply not enough data to have a clear answer. Untreated severe pain in the mother may also be harmful to the fetus.” He noted that, when possible, other treatments and therapies should be the first-line treatment before opioids.

ASA last month distributed a Choosing Wisely® list as part of the ABIM Foundation’s campaign to help physicians and patients engage in conversations about what treatments or medications are commonly prescribed in pain medicine, but aren’t always necessary.  Number-one on ASA’s list: don’t prescribe opioid analgesics as first-line therapy to treat chronic non-cancer pain.