Neonatal abstinence syndrome (NAS) is a group of withdrawal symptoms that newborns experience after being exposed to certain drugs, most commonly opioids, during pregnancy. When a pregnant person regularly uses opioids or certain other substances, those drugs cross the placenta and the developing baby becomes physically dependent on them. After birth, the supply is cut off, and the baby goes through withdrawal. In recent years, NAS has affected roughly 4 to 5 out of every 1,000 hospital births, nearly doubling from about 2.6 per 1,000 births a decade earlier.
What Causes It
Opioids are the most common cause. That includes prescription painkillers, heroin, and medications used to treat opioid use disorder such as methadone and buprenorphine. Even when a pregnant person is receiving supervised medication-assisted treatment, the baby can still develop NAS, because the medication itself crosses the placenta. This does not mean treatment should be stopped during pregnancy. Untreated opioid use disorder carries far greater risks to both parent and baby.
Other substances can also trigger withdrawal in newborns, though less commonly. Sedatives like barbiturates and certain anti-anxiety medications are known causes. The severity and timing of symptoms depend on which drug was used, how long the exposure lasted, how frequently it was taken, and how far along the pregnancy was when exposure occurred.
How Symptoms Appear
The hallmark signs of NAS are increased muscle tone, tremors while the baby is at rest, and an exaggerated startle reflex. Beyond that triad, symptoms show up across the baby’s entire body because withdrawal puts the nervous system into overdrive.
Nervous system symptoms include high-pitched, inconsolable crying, jitteriness, trouble sleeping, and difficulty calming down. In severe cases, seizures are possible. The baby’s body also struggles to regulate its basic functions: heart rate and breathing may speed up, temperature can swing high or low, and the skin may look blotchy or sweaty. Frequent yawning, sneezing, and nasal stuffiness are surprisingly common signs. Feeding problems are also typical. Babies with NAS often eat poorly, spit up frequently, vomit, and develop diarrhea, which can lead to dehydration and weight loss.
Timing depends on the substance. Withdrawal from heroin, a short-acting opioid, usually shows up within the first 24 to 48 hours of life. Buprenorphine withdrawal appears a bit later, around 36 to 60 hours. Methadone, which is longer-acting, tends to trigger symptoms at 48 to 72 hours. Sedative withdrawal can take much longer to surface: up to 7 days for barbiturates and as long as 21 days for some anti-anxiety medications. This wide range means some babies seem fine at first and only develop symptoms days after birth.
How It’s Assessed
For nearly 50 years, hospitals have relied on the Finnegan Neonatal Abstinence Scoring System to gauge how severe a baby’s withdrawal is. The Finnegan score evaluates 32 clinical signs, each rated on a scale, with a maximum possible score of 46. Nurses assess the baby at regular intervals, and if scores consistently exceed a set threshold, medication may be started.
A newer approach called “Eat, Sleep, Console” has been gaining ground. Instead of tracking dozens of individual signs, it asks three straightforward questions: Can the baby eat well enough? Can the baby sleep for at least an hour at a stretch? Can the baby be consoled within a reasonable time? A major trial published in the New England Journal of Medicine found that babies managed with Eat, Sleep, Console were ready for hospital discharge in an average of 8.2 days, compared to 14.9 days under the traditional Finnegan-based approach. That is nearly a week less in the hospital. The Eat, Sleep, Console model appears to reduce the number of babies who need medication without compromising their safety.
Non-Drug Care That Makes a Difference
The first line of treatment for NAS is not medication. It is a set of environmental and comfort measures designed to keep a withdrawing baby calm and nourished. These interventions sound simple but have measurable effects on how long symptoms last and whether medication becomes necessary.
Swaddling tightly in a blanket decreases arousal, prolongs sleep, and helps the baby develop better self-regulation. Keeping the room quiet and dimly lit prevents overstimulation in a nervous system that is already on high alert. Skin-to-skin contact with a parent helps regulate the baby’s temperature, heart rate, and stress level. Breastfeeding, when appropriate, provides both nutrition and comfort.
Rooming-in, where the baby stays in the same room as the parent rather than being transferred to a separate intensive care unit, is one of the most impactful non-drug strategies. A review of six studies found that babies who roomed in with their mothers were 63% less likely to need medication compared with those in standard intensive care. One study reported that when parents were present 100% of the time, hospital stays were about 9 days shorter, treatment duration dropped by 8 days, and withdrawal severity scores decreased. Parental presence is not just comforting. It is genuinely therapeutic.
When Medication Is Needed
When comfort measures alone aren’t enough to control severe symptoms, babies receive small doses of an opioid, typically oral morphine or methadone, to ease the withdrawal gradually. The idea is the same as tapering an adult off a drug: provide a controlled, slowly decreasing dose so the nervous system can adjust without the distress of abrupt withdrawal. Once the baby stabilizes, the medication is reduced in small steps over days to weeks.
There is no single standardized protocol. Dosing regimens vary from hospital to hospital, and the American Academy of Pediatrics acknowledges that data supporting specific starting doses are limited. What matters most is close monitoring: frequent reassessment of the baby’s symptoms, careful adjustment of the dose, and a slow enough taper to prevent rebound withdrawal.
Hospital Stay and What to Expect
The length of a hospital stay for NAS depends on the substance involved, the severity of symptoms, and the care approach used. Under traditional management, the average stay runs close to two weeks or longer. Babies treated with the Eat, Sleep, Console model tend to go home sooner, often around 8 days. Babies who need medication generally stay longer than those managed with comfort measures alone, since the tapering process takes time.
During the hospital stay, the baby is monitored closely for weight gain, feeding tolerance, temperature stability, and overall comfort. Parents are typically encouraged to be as involved as possible. Holding, feeding, and soothing the baby aren’t just allowed, they are a core part of treatment.
Long-Term Developmental Effects
Withdrawal symptoms themselves resolve within weeks, but the effects of prenatal opioid exposure can extend into childhood. Children with a history of NAS are more likely to experience delays in cognitive development, speech and language skills, and motor ability. Speech or language impairment is the most frequently identified educational disability in this group, and speech therapy is the most commonly received service.
As these children reach school age, the pattern of challenges often shifts. Behavioral problems, difficulty with executive function (the ability to plan, focus, and manage impulses), and declining academic performance become more prominent. Studies using large educational databases confirm that children with a history of NAS are referred for special education services at higher rates than their peers. Early intervention, including developmental screening and therapy services, can help close some of these gaps, which is why follow-up care after hospital discharge matters just as much as the initial treatment.