What is the incidence of neonatal abstinence syndrome (NAS) in the US?

Updated: Dec 20, 2017
  • Author: Ashraf H Hamdan, MD, MBBCh, MSc, MRCP, FAAP; Chief Editor: Santina A Zanelli, MD  more...
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Answer

Neonatal drug withdrawal is a common problem in populations in which drugs taken for therapeutic, recreational, or addiction purposes are readily available to pregnant women. However, the incidence is difficult to determine because it is not uniformly tracked, [1] because of unreliable histories of maternal drug abuse, and because of limited health provider skills in eliciting drug histories and diagnosing nonopiate drug exposure in the newborn period. In addition, maternal use of more than one drug makes ascribing a given effect on the neonate to a specific drug difficult. One reported estimate was 3.39 per 1,000 hospital births (13,500 newborns). [1]

In the United States, substance use among pregnant and postpartum women is a public health issue. An estimated one third of childbearing women take prescription opioids. [22]  A pooled analysis of data from the 2009-2013 National Survey on Drug Use and Health (NSDUH) revealed 0.9% of pregnant women met criteria for opioid analgesics, and 0.2% met the criteria for heroin. [1]

Between 2004 and 2013, neonatal abstinence syndrome (NAS) quadrupled and hospital length of stay increased from 13 days to 19 days, resulting in 7-fold increases neonatal intensive care unit stays for NAS. [22]

In 2011-2012, the NSDUH in the United States found that 5.9% of pregnant women aged 15-44 years reported using illicit drugs, compared with 10.7% of nonpregnant women in this age group. [23] The rate of illicit drug use among pregnant women aged 15-17 years was 18.3%, 9% among pregnant women aged 18-25 years, and 3.4% among pregnant women aged 26-44 years. [23]

In the 2013 report, among pregnant women aged 15-44 years, an estimated 8.5% reported current alcohol use, 2.7% reported binge drinking, and 0.3% reported heavy drinking. These rates were lower than the rates for nonpregnant women in the same age group (55.5, 24.7, and 5.2%, respectively). [23] In the same report, first trimester consumption was 17.9%, compared with significantly lower reporting during the second (4.2%) and third (3.7%) trimesters.

According to data from the Treatment Episode Data Set (TEDS), the proportion of female substance abuse treatment admissions aged 15 to 44 who were pregnant at treatment entry remained relatively stable between 2000 and 2010 (4.4 and 4.8 percent). However, there were shifts in the types of substances reported by these treatment admissions. The percentage of pregnant admissions reporting alcohol abuse (with or without drug abuse) decreased from 46.6 percent in 2000 to 34.8 percent in 2010, and the percentage reporting drug abuse but not alcohol abuse increased from 51.1 percent in 2000 to 63.8 percent in 2010. [24]

About 1 in 6 pregnant women aged 15-44 years had smoked cigarettes in the past month, based on combined data for 2011 and 2012. The rate of past-month cigarette use was lower among those who were pregnant (15.9%) than it was among those who were not pregnant (24.6%). This pattern was also evident among women aged 18-25 years (20.9 vs. 28.2 for pregnant and nonpregnant women, respectively) and among women aged 26-44 years (12.5 vs. 25.2, respectively). However, among those aged 15-17 years, the rate of cigarette smoking was higher for pregnant women than nonpregnant women (22.7% vs 13.4%). [23]

Data from the 2009 NSDUH report provide indirect evidence of dramatic increases in the prevalence of substance use following childbirth. Marijuana use was higher for recent mothers with children younger than 3 months in the household (3.8%) than for women in the third trimester of pregnancy (1.4%), suggesting resumption of use among mothers in the first 3 months after childbirth. [25]

Overall the incidence of drug-exposed newborns is reportedly 3-50%, depending on the specific patient population, with urban centers usually reporting higher rates. An estimated 10–11% of the 4.1 million live births (in 2005) involved prenatal exposure to alcohol or illegal drugs. When tobacco data are included more than one million children are affected by prenatal exposure. Among offspring exposed to opioids or heroin in utero, withdrawal signs develop in 55-94%.

Patrick et al reported that from 2000-2009, the rate of newborns diagnosed with NAS increased from 1.20 (95% CI, 1.04-1.37) to 3.39 (95% CI, 3.12-3.67) per 1000 hospital births per year. During the same period, total hospital charges for NAS are estimated to have increased from $190 million (95% CI, $160-$230 million) to $720 million (95% CI, $640-$800 million), adjusted for inflation. In 2009, the estimated number of newborns with NAS was 13,539 (95% CI, 12 441-14 635) or approximately 1 infant born per hour in the United States with signs of drug withdrawal. [6]


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