A study published online in JAMA reveals that the rate of mothers abusing opiates during pregnancy has increased by almost five times between 2000 and 2009 in the United States. In addition, the researchers found that the number of newborns with drug withdrawal symptoms (neonatal abstinence syndrome [NAS]) has increased by almost three times and has significantly increasing hospital costs.

According to results from a recent study 16.2% of pregnant teens and 7.4% of pregnant women aged 18 to 25 years take illegal drugs.

The researchers explain:

NAS “most commonly occurs in the context of antepartum [before birth] opiate use, although other drugs have also been implicated. In addition to NAS, illicit drug use (specifically opioid dependence) during pregnancy is associated with a significantly increased risk of adverse neonatal outcomes such as low birthweight (

Symptoms of NAS include:

  • Tremors
  • Respiratory distress
  • Seizures
  • Feeding intolerance
  • Increased irritability
  • Hypertonia (heightened muscle tone)

According to the researchers, 60% to 80% of newborns exposed to heroin or methadone in utero have displayed symptoms of withdrawal associated with NAS. To date, there have been no estimates of the national incidence of NAS across the United States in the context of opiate use during pregnancy.

In order to examine patterns in the national incidence of NAS and maternal opiate use at the time of delivery and to characterize trends in national health care expenditures associated with NAS between 2000 and 2009, Stephen W. Patrick, M.D. M.P.H., M.S., of the University of Michigan Health System, Ann Arbor, Mich., and his team used the Kids’ Inpatient Database (KID) to identify newborns with NAS by International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code.

In addition, the team used The Nationwide Inpatient Sample (NIS) in order to identify mothers using diagnosis related groups for vaginal and cesarean deliveries. The researchers identified clinical conditions using ICD-9-CM diagnosis codes.

The researchers found that between 2000 and 2009, the number of infants born with NAS increased from 1.20 to 3.39 per 1,000 hospital births per year, while the rate of mothers using or dependent on opiates rose from 1.19 to 5.63 per 1,000 births.

The researchers explained:

“Compared with all other hospital births, newborns with NAS were significantly more likely to have respiratory diagnoses (30.9%), to have low birthweight (19.1%), have feeding difficulties (18.1%), and have seizures (2.3%). Newborns with NAS were also more likely to be covered by Medicaid (78.1%) and reside in zip codes within the lowest income quartile (36.3%).”

During this time period, average hospital charges for infants with NAS increased by 35% – increasing from $39,000 in 2000 to $53,400 in 2009. The length of time newborns diagnosed with NAS stayed in hospital averaged 16 days and remained relatively unchanged during the study period.

Furthermore, the total associated hospital costs for NAS increased from $190 million in 2000 to $720 million in 2009.

In 2009, the estimated number of infants diagnosed with NAS was 13,539 (about 1 infant born per hour in the U.S. with symptoms of NAS).

The researchers conclude:

“In conclusion, newborns with NAS experience longer, often medically complex and costly initial hospitalizations. The increasing incidence of NAS and its related health care expenditures call for increased public health measures to reduce antenatal exposure to opiates across the United States.

In addition, further innovation and standardization of treatment of NAS may mitigate NAS symptoms and reduce hospital LOS. States are poised to seek innovative solutions to decrease the burden of NAS, because the majority of hospital expenditures for this condition are shouldered by state Medicaid programs.”

In an associated report, Marie J. Hayes, Ph.D., of the University of Maine, Orono, and Mark S. Brown, M.D., of Eastern Maine Medical Center, Bangor, explain that:

“Future directions in NAS research must address the need for clinical trials of new medications to establish optimal protocols for maternal opiate dependence with particular focus on methadone treatment induction of the mother early in pregnancy, maternal adherence to treatment, ancillary alcohol use monitoring, and psychiatric care.”

They continue:

“Postnatally, early identification and aggressive opiate replacement in infants with early signs of NAS may help to decrease severity and LOS. As suggested by Patrick et al and other studies, breastfeeding may reduce treatment rate and LOS in opiate-exposed infants in all categories.

Clues to fetal-neonatal dependence and NAS risk are emerging from studies of placental transfer of opiates across gestation, relation to maternal dose change, infant pharmacogenomics, and meconium [stool of an infant] metabolites to determine other exposures. This additional information may lead to better postnatal care of infants with NAS.”

Written By Grace Rattue