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NIH-funded study emphasizes lack of information about prenatal opioid exposure
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A review published in Pediatrics revealed gaps and inconsistencies in findings about the outcomes of children exposed to opioids prenatally and those born with neonatal abstinence syndrome, or NAS.
The review was funded by the NIH to better understand the impact of a child’s environment on their development.
“At this point, we do not know which newborns will develop NAS and which ones will not,” study researcher Elisabeth Conradt, PhD, assistant professor of developmental psychology and health psychology at the University of Utah, told Infectious Diseases in Children. “If we had this information, we could start intervening at birth to prevent or lessen NAS symptoms.”
Conradt added that many recent and “exciting” studies demonstrate the benefits of nonpharmacologic care for opioid-exposed neonates.
The researchers noted that the rate of opioid exposure during pregnancy skyrocketed 333% between 1999 and 2014, and prenatal opioid exposure affected nearly 26,000 infants in the United States in 2014 alone. Between 50% and 80% of infants exposed to opioids prenatally develop NAS, they wrote.
The first studies on the effects of prenatal opioid exposure at birth did not highlight many consequences of exposure. Some researchers reported hypertonia; jerky, tremulous or hyperactive qualities; poor attention; and irritability, but they also reported that these infants demonstrated a greater ability to self-soothe compared with controls. Conradt and colleagues noted that these studies had small sample sizes and did not consider confounding factors such as prenatal tobacco or alcohol exposure and maternal age.
After the 2002 approval of buprenorphine for the treatment of opioid addiction in pregnant women, studies compared the outcomes of newborns born to mothers on the medication with those receiving methadone — the previous standard of care. The researchers wrote that although infants born to mothers taking buprenorphine had mild NAS symptoms, their condition was not as severe compared with those born to mothers taking high-dose methadone. However, other studies demonstrated no significant neurobehavioral differences.
According to Conradt and colleagues, only six of the 21 studies were published in the last 5 years on the neurodevelopmental outcomes of infants exposed to opioids in utero. Both older and newer studies demonstrated inconsistent findings and had small sample sizes.
The researchers highlighted one recent study published in Drug and Alcohol Dependence in 2018 that included 131 infants exposed to opioids prenatally. These children had few neurodevelopmental effects in infancy and developed normally.
Studies on the long-term outcomes of prenatal opioid exposure also varied. Conradt and colleagues wrote that some data suggested no cognitive differences between children exposed to opioids in utero and those who were not, whereas others reported differences in IQ as well as neurologic and language performance. However, these effects differed based on confounding factors.
“It has been impossible for us to come to any firm conclusion about the developmental consequences of prenatal opioid exposure because of the limitations of the existing data,” Conradt said. “We need large, prospective, longitudinal studies that carefully measure the quality of the caregiving environment so that we can better understand how prenatal opioid exposure and associated environmental exposures could impact child health outcomes.” – by Katherine Bortz
Reference:
Conradt E, et al. Pediatrics. 2019;doi:10.1542/peds.2019-0128.
Kaltenbach K, et al. Drug Alcohol Depend. 2018;doi:10.106/j.drugalcdep.2017.11.030.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Stephen W. Patrick, MD, MPH, MS
As the opioid crisis expands across the U.S., increasing numbers of pregnant women and infants are affected. Understanding how opioid exposure may affect an infant’s development is important to patients, providers, educators and policymakers; however, as the review by Conradt and colleagues points out, the current state of research in this area is lacking.
Much of the existing research does not account for important confounders (eg, alcohol use, lack of prenatal care, maternal illness) that may also influence infant development. Because of these limitations, we should be cautious as we interpret this existing literature. Moving forward, the authors provide a framework for how rigorous research could be conducted to address these fundamental questions. They also provide hope that the NIH-funded [Environmental Influences on Child Health] initiative may be the vehicle to finally provide an understanding of the effects of opioid exposure on long-term developmental outcomes.
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