Neonatal abstinence syndrome (NAS) is a constellation of physiologic and neurobehavioral signs exhibited by newborns exposed to addictive prescription or illicit drugs taken by a mother during pregnancy (1). The number of hospital discharges of newborns diagnosed with NAS has increased more than 10-fold (from 0.4 to 4.4 discharges per 1,000 live births) in Florida since 1995, far exceeding the three-fold increase observed nationally (1,2). In February 2014, the Florida Department of Health requested the assistance of CDC to 1) assess the accuracy and validity of using Florida’s hospital inpatient discharge data, linked to birth and infant death certificates, as a means of NAS surveillance and 2) describe the characteristics of infants with NAS and their mothers. This report focuses only on objective two, describing maternal and infant characteristics in the 242 confirmed NAS cases identified in three Florida hospitals during a 2-year period (2010–2011). Infants with NAS experienced serious medical complications, with 97.1% being admitted to an intensive care unit, and had prolonged hospital stays, with a mean duration of 26.1 days. The findings of this investigation underscore the important public health problem of NAS and add to current knowledge on the characteristics of these mothers and infants. Effective June 2014, NAS is now a mandatory reportable condition in Florida. Interventions are also needed to 1) increase the number and use of community resources available to drug-abusing and drug-dependent women of reproductive age, 2) improve drug addiction counseling and rehabilitation referral and documentation policies, and 3) link women to these resources before or earlier in pregnancy.

For this study, six hospitals in two Florida counties with high numbers of NAS births were identified using Florida’s hospital inpatient discharge data; of these, three hospitals were able to provide data needed for this investigation. Three data sources were used to identify infants with possible NAS: linked administrative data (Florida’s linked hospital inpatient discharge, birth certificate, and infant death certificate data), data collected through neonatal intensive care unit (NICU) admission logs, and inpatient pharmacy data. The linked administrative data selection criteria were maternal residency in Florida, nonadoption status of the infant, and birth of the infant at one of the three participating hospitals during 2010–2011. Infants with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) discharge diagnosis code of 779.5 (drug withdrawal syndrome in a newborn) or 760.72 (narcotics affecting fetus or newborn via placenta or breast milk) were considered to have possible NAS. NICU staff provided the investigation team with a list of infants admitted to the NICU for NAS treatment, based on documentation in NICU admission logs. Additionally, inpatient pharmacy dispensing data were used to identify infants treated with morphine, methadone, or clonidine during the 2-year period.

Infant and maternal medical records were abstracted. Infants meeting all three of the following criteria were classified as having confirmed NAS (hereafter referred to as NAS): 1) presence of a constellation of clinical signs consistent with NAS (defined as a documented NAS score >8 [on a scale of 0–37]) (3), not explained by another etiology; 2) documented history of maternal use during pregnancy of prescription or illicit drugs associated with NAS (1) or laboratory confirmation of recent maternal drug use or fetal exposure to such drugs; and 3) a severity of illness that resulted in a prolonged (>2 days) neonatal hospitalization. Descriptive statistics for infants with NAS were calculated by comparing infant data abstracted from medical records with data obtained from the linked administrative data on all infants (excluding medical record numbers of infants with NAS) born at the participating hospitals during the 2-year period. Z-tests were used to compare population proportions, and t-tests were used to compare means.

The linked administrative data identified 179 infants with ICD-9-CM codes 779.5 or 760.72. An additional 234 unique infants were identified from the NICU and pharmacy data, for a total of 413 infants with possible NAS whose medical records were reviewed, along with their mother’s medical record (when available). Of the 413 infants, 242 infants were classified as having NAS. There were 22,285 infants without NAS identified in the linked administrative data.

The mean age of mothers of infants with NAS was slightly younger, at 27.4 years, compared with 28.2 years for mothers of infants without NAS (p=0.01) (Table 1). Most of the infants with NAS (82.6%) were non-Hispanic white, compared with 56.7% of infants without NAS (p<0.01). There was a significantly higher percentage of low birth weight (<2500 grams; 19.4% versus 8.0%) and preterm (<37 weeks gestation) delivery (18.2% versus 12.3%) among infants with NAS compared with infants without NAS. Almost all infants with NAS (97.1%) were admitted to the NICU, compared with 6.2% of infants without NAS. None of the infants with NAS died during their birth hospitalization.

The mean of the first documented NAS score >8 was 11.5 (Table 2). Urine toxicology screens were the most common type of screen performed on infants with NAS, with 86.4% of infants with NAS screened for substance exposure. Pharmacologic therapy to control signs of NAS was used in 89.7% of infants, with morphine being the most commonly selected treatment (used in 87.6% of cases), followed by phenobarbital (used in 36.8% of cases). The mean NICU length of stay for infants with NAS was 26.1 days, and their mean age at discharge was 27.4 days. At discharge, most infants with NAS were receiving formula only (94.6%), approximately 4% were receiving both breast milk and formula, and none were documented as being exclusively breastfed.

There was documentation in the medical records of opioid use during pregnancy for nearly all (99.6%) mothers of infants with NAS. Approximately 82% of mothers were reported as using one or more opioid such as oxycodone, morphine, hydrocodone, hydromorphone, tramadol, or meperidine; 59.9% as using methadone; and 3.7% as using buprenorphine. Less than 1% of mothers were reported to have used heroin during pregnancy. Benzodiazepines were the second most commonly reported substances used (40.5%), followed by tobacco (39.7%), marijuana (24.4%), and cocaine (14.1%). Reasons reported for opioid use included illicit (i.e., nonmedical) (55.0%), drug abuse treatment (41.3%), and chronic pain treatment (21.5%). The reason for opioid use during pregnancy was unknown for 10.3% of NAS mothers. Urine toxicology screens were performed on 86.8% of the mothers of infants with NAS; of these, 90.5% had positive urine screen results. Lastly, 10.3% of mothers had documentation in the medical records that they had received or were referred for drug addiction rehabilitation or counseling during the infant’s birth hospitalization.