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Key Findings: Maternal Treatment with Opioid Analgesics and Risk for Birth Defects

Physician talking with woman about medications

The American Journal of Obstetrics and Gynecology has published a new CDC study: “Maternal Treatment with Opioid Analgesics and Risk for Birth Defects”. You can read the abstract of the article here. The findings from this article are summarized in the following text.

Main Findings from this Study

  • Treatment with opioid analgesics was linked with the following birth defects:
  • Treatment with opioid analgesics just before or during early pregnancy was reported by 2% to 3% of the mothers.
  • Codeine and hydrocodone were the most frequently reported medications, representing 69% of all reported opioid analgesics used.
  • Commonly reported reasons for treatment with opioid analgesics during pregnancy included surgical procedures, infections, chronic diseases, and injuries.

Treatment Decisions

When making treatment decisions just before or during pregnancy, it is important that women and their doctors weigh the benefits of opioid analgesic medications along with their potential risks for birth defects, including some types of congenital heart defects, which are important contributors to infant morbidity and mortality.

The findings related to congenital heart defects were consistent with findings of previous studies showing links between the use of codeine during the first trimester and the occurrence of some heart defects. Congenital heart defects are among the most common birth defects, affecting nearly 1% of U.S. births, and are the main contributor to infant death attributable to birth defects. As mentioned earlier, previous studies have suggested that treatment with opioid analgesics might increase the risk for cleft lip and palate. However, in this study, the occurrence of cleft lip and palate did not appear to be linked with treatment with opioid analgesics.

In this study, the findings related to some of the other birth defects were observed for the first time. For example, links between the use of opioid analgesics and the occurrence of hydrocephaly, glaucoma, or gastroschisis have not been observed in previous studies and deserve further investigation.

About Opioid Analgesics and this Study

Opioid analgesics are prescription medications that commonly are used to treat severe pain. Two common opioid medications are codeine and oxycodone. Lower doses of opioids also might be included in some cough medicines. The effects of opioids on a pregnant woman and her unborn baby are not well understood. Previous studies looking at opioid analgesics and birth defects have had inconsistent findings. However, some have suggested that these medications might increase the risk for heart defects or cleft lip and palate.

For this study, researchers aimed 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. Population-based means that the study looked at all babies with birth defects whose mothers lived in the study region, which is important to make sure that study results apply to the U.S. population in general.

Medication During Pregnancy: CDC Activities

About 1 in every 33 babies is born with a birth defect1. Birth defects are one of the leading causes of infant deaths, accounting for more than 20% of all infant deaths2. CDC is working with its partners and the public to build a comprehensive approach to improve understanding of medication use during pregnancy.

  • Research: CDC funds a large study of birth defects called the National Birth Defects Prevention Study. This study is working to identify risk factors for birth defects and to answer questions about some medications taken during pregnancy.
  • Technical expertise: CDC works with staff from the U.S. Food and Drug Administration (FDA) and other professionals to help conduct studies on the effects of medication use during pregnancy and ways to prevent harmful effects.
  • Collaboration: As part of the Treating for Two: Safer Medication Use in Pregnancy Initiative, CDC established an interagency coalition of partners to develop a formal review process to evaluate the quality and strength of existing evidence for risks associated with medications used during pregnancy.

More Information

To learn more about medication use during pregnancy, please visit
For more information about birth defects, please visit CDC’s birth defects homepage.

  1. Centers for Disease Control and Prevention. Update on Overall Prevalence of Major Birth Defects–Atlanta, Georgia, 1978-2005. MMWR Morb Mortal Wkly Rep. 2008;57(1):1-5.
  2. Mathews TJ, MacDorman MF. Infant mortality statistics from the 2008 period linked birth/infant death data set. National vital statistics reports; vol 60 no 5. Hyattsville, MD: National Center for Health Statistics. 2012.