The CDC released the findings of their new study published last week in The American Journal of Obstetrics and Gynecology indicating that taking opioid painkillers such as codeine, hydrocodone or oxycodone shortly before or during early pregnancy may increase the risk of birth defects.
If you find yourself in this situation, please don't panic. Although the headline is technically true, the risk is still very low. Please read the rest of this post to learn more about what this study found.
Study Design and Results
The purpose of the study was to see if treatment with any opioid analgesic medication just before or during early pregnancy was associated with the occurrence of certain birth defects. The study used data from the National Birth Defects Prevention Study, a population-based, case-control study to understand the causes of and risk factors for major birth defects in the United States.
Researchers found that 2%-3% of the mothers interviewed were treated with prescription opioid pain killers, or analgesics, just before or during early pregnancy. Illicit use of these medications was not examined. Codeine and hydrocodone were the most frequently reported medications, representing 69% of all reported opioid analgesics used.
The following birth defects were linked with opioid treatment:
- Spina bifida (a type of neural tube defect)
- Hydrocephaly (build up of fluid in the brain)
- Glaucoma (an eye defect)
- Gastroschisis (a defect of the abdominal wall)
- Congenital heart defects
The study found that women who took prescription opioid medications just before or during early pregnancy had about two times the risk for having a baby with hypoplastic left heart syndrome (one of the most critical heart defects) as women who were not treated with these opioid medications.
"It's important to acknowledge that although there is an increased risk for some types of major birth defects from an exposure to opioid analgesics, that absolute risk for any individual woman is relatively modest," said the study's lead author, Cheryl S. Broussard, Ph.D., CDC's National Center on Birth Defects and Developmental Disabilities. "However, with very serious and life threatening birth defects like hypoplastic left heart syndrome, the prevention of even a small number of cases is very important.
Very little is actually known about the safety of most medications when it comes to their use by pregnant women. No one wants to jeopardize the health of a baby by testing drugs on the expectant mother, so all we usually have available is after-the-fact information. Since many different factors can affect a pregnancy, it's hard to know if one specific medication taken is the sole cause of a birth defect.
It's very difficult to assess the significance of this study without being able to see specific data. As of yet, I haven't been able to get access to the full journal article, although I am continuing to try.
One piece of information I'd like to know is just how great the risk is –– in real numbers. Saying the risk of a certain heart defect is double if you take opioids really doesn't say anything. If the risk is one out of four, then doubling that to two out of four is very significant. However, if the risk is one out of 10,000, then doubling it to two out of 10,000 is still very low. Since the lead author made a point of saying that the risk for any individual mother is “relatively modest,” I suspect my second example may be closer in this case.