Common Terminology and Diagnoses in the Neonatal Intensive Care Unit

The neonatal intensive care unit (NICU) cares for infants requiring specialty care. This page addresses the terminology and diagnoses that you may commonly encounter in the NICU. See ASHA’s Practice Portal page on the NICU for more information about the practice setting and the roles of audiologists and speech-language pathologists in the NICU.

Terminology

Defining the Ages of Fetuses and Newborns

NICU staff use standardized terminology when defining ages and comparing outcomes of fetuses and newborns. The terms are as follows (American Academy of Pediatrics Committee on Fetus and Newborn, 2004):

• Gestational age (GA) or fetal age (completed weeks): time elapsed between the first day of the last menstrual period and the day of delivery. If pregnancy was achieved using assisted reproductive technology, GA is calculated by adding 2 weeks to the conceptional age.
• Chronological age (days, weeks, months, or years): time elapsed from birth.
• Postmenstrual age (weeks): GA plus chronological age.
• Corrected age (weeks or months): chronological age reduced by the number of weeks born before 40 weeks’ gestation. The term should be used only for children up to 2 years of age who were born preterm. Preterm infants are adjusted to the corrected age and then follow the typical developmental milestone trajectory. See ASHA’s resource on developmental milestones for communication and feeding skills.

GA Classification

Prematurity is defined as any infant born alive before 37 completed weeks of pregnancy. There are subcategories of prematurity based on GA at birth (American Academy of Pediatrics Committee on Fetus and Newborn, 2004; World Health Organization, 2022).

Extremely preterm: infants born at or before 28 weeks’ gestation

Very preterm: infants born at or before 32 weeks’ gestation

Moderately preterm: infants born between 32 and 34 weeks’ gestation

Late preterm: infants born between 34 and 36 weeks’ gestation

Birthweight Classification

The NICU also categorizes infants based on birthweight, regardless of GA at birth (American Academy of Pediatrics Committee on Fetus and Newborn, 2004; World Health Organization, 2022).

Extremely low birthweight (ELBW): infants born weighing less than 1,000 g

Very low birthweight (VLBW): infants born weighing less than 1,500 g

Low birthweight (LBW): infants born weighing less than 2,500 g

Small for gestational age (SGA): infants born weighing less than the 10th percentile for weight

Appropriate for gestational age (AGA): infants born weighing between the 10th and 90th percentiles for weight

Large for gestational age (LGA): infants born weighing greater than the 90th percentile for weight

Common Diagnoses in the NICU

Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a type of chronic lung disease. BPD is the long-term breathing issues in preterm infants that may result from underdeveloped lungs (hypoplasia) or from lung injury that affects 49.8% of extremely preterm neonates (Bell et al., 2022). Lung injury can occur from necessary medical care such as mechanical ventilation or oxygen use. Severe lung disease may result in the need for tracheostomy and long-term ventilation, at-home oxygen use, temporary or permanent feeding tubes, and/or mild-to-profound dysphagia.

Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) can occur from the diaphragm not closing properly in fetal development, causing abdominal organs to herniate into the chest (Kosiński & Wielgoś, 2017). CDH may be an isolated event or associated with chromosomal or genetic conditions. CDH may lead to underdeveloped lungs, respiratory distress, or pulmonary hypertension. Medical and surgical treatments for CDH include mechanical ventilation and/or extracorporeal membrane oxygenation (ECMO) and surgical repair of the defect. These necessary medical and surgical treatments often result in the following:

• extended time not feeding by mouth
• lack of feeding exposure and experience
• abdominal discomfort
• repeated exposure to painful and stressful stimuli

As a result, infants with CDH may have long-term feeding and swallowing difficulties—in addition to cardiorespiratory problems, poor growth, and developmental delays.

Gastroschisis

Gastroschisis occurs when a fetus’s intestines herniate, or protrude, through the abdominal wall and grow outside of the body in the amniotic fluid. The unprotected intestine becomes irritated, causing it to swell and shorten. The longer the exposure to amniotic fluid, the more likely the intestine will become damaged. As the fetus continues to develop, the tight opening may reduce blood supply to the intestine or cause a malrotation—resulting in inflammation and/or intestinal blockage, loss, or malfunction.

Necessary medical treatments and interventions for gastroschisis—such as mechanical ventilation, extended time not feeding by mouth, and surgical interventions—can lead to abdominal discomfort, lack of feeding exposure and experience, and repeated exposure to painful or stressful stimuli. Therefore, children born with gastroschisis may have feeding and/or swallowing problems, including problems with digestion, nutrition, and growth.

Hypoxic Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) is a type of anoxic brain injury that occurs during or shortly after birth in 3.0%–5.5% of full-term NICU infants (Mendoza & Lutz, 2022; Talisman et al., 2022). The length of time and areas of the brain without oxygenation and blood flow usually determine the severity of the injury. HIE can occur for a variety of reasons, including the following:

• disrupted blood flow to the placenta (abruption)
• preeclampsia
• fetal infections
• fetal alcohol or drug exposure
• umbilical cord prolapse
• prolonged labor
• cardiac arrest

Infants with HIE may present with neurological irritability, hyper- or hypotonia, seizures, and feeding and swallowing difficulties. Severe HIE may have developmental impairments including—but not limited to—cerebral palsy, seizures, and stroke. HIE can impact feeding and/or swallowing in several different ways. Examples are as follows:

• inability to maintain an alert state
• neuromotor deficits
• pharyngeal dysphagia

Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is when an infant is smaller than they should be for GA, weighing less than the 10th percentile for their GA. There are two types of IUGR:

1. Symmetric—all fetal body parts are the same size.
2. Asymmetric—only the abdomen is small; the head and the brain are typically sized.

IUGR occurs in 21.6% of full-term NICU infants and is most commonly due to

• maternal health issues—such as hypertension, heart disease, and autoimmune conditions;
• teratogens—such as smoking and alcohol consumption; and
• pregnancy issues—such as placental or umbilical cord abnormalities and multiple gestation (Ku et al., 2021).

Infants with IUGR face many acute problems before, during, and after birth. Problems include increased risks of preterm birth, infections, respiratory illness, and long-term neurodevelopmental delays (Sharma et al., 2016). IUGR is a major cause of neonatal mortality and morbidity (Sharma et al., 2016).

Intraventricular Hemorrhage

Intraventricular hemorrhage (IVH) is bleeding inside or around the ventricle, or the spaces in the brain that contain the cerebral spinal fluid. IVH is most common in preterm infants, especially low-birthweight infants, and usually occurs in the first 72 hours of life. Severe intracranial hemorrhage occurs in 14.3% of extremely preterm infants but varies across GA. Approximately 38% of infants born at 22 weeks exhibit intracranial hemorrhage, compared to 5.3% of those born at 28 weeks’ gestation (Bell et al., 2022).

IVH is described in the following four grades, depending on the amount and location of bleeding (Bowerman et al., 1984):

• Grade 1—bleeding is confined to the specific areas of the fetus’s brain, known as the subependymal region or germinal matrix.
• Grade 2—bleeding has extended into the ventricle, filling 50% or less of the ventricle’s volume.
• Grade 3—extensive bleeding has filled more than 50% of the ventricle, causing the ventricle to enlarge.
• Grade 4—bleeding in the brain tissue surrounding the ventricle. This may also be referred to as a periventricular hemorrhagic infarction.

The exact reason why IVH occurs is not well understood, but it may result from anoxia due to a difficult or traumatic birth or from complications after delivery. Bleeding can occur because blood vessels in a premature baby’s brain are very fragile and easily rupture. Babies with respiratory problems or other complications of prematurity are more likely to have IVH.

IVH was strongly associated with white-matter damage. White-matter damage was associated with an increased risk of hydrocephalus, cerebral palsy, impaired early mental and motor development, and visual dysfunctions (O’Shea et al., 2012).

Laryngomalacia/Tracheomalacia

Both laryngomalacia and tracheomalacia are conditions affecting the airway. Laryngomalacia refers to weak structures of the larynx; such weakness causes airway collapse during inspiration. Tracheomalacia refers to weak cartilage of the trachea; this weakness causes airway collapse during expiration. Symptoms may include respiratory distress, noisy breathing or stridor, and poor oral intake. The classic appearance of the larynx of an infant with laryngomalacia will include arytenoid collapse, short aryepiglottic folds, and an epiglottis that is curled inward. Treatment may include positioning precautions and/or medications for gastric reflux—as well as feeding strategies to reduce the risk of aspiration and improve suck–swallow–breathe coordination. More severe cases may require surgical interventions.

Meconium Aspiration Syndrome

Meconium aspiration syndrome (MAS) occurs when a newborn infant aspirates a mixture of meconium (a newborn’s first bowel movement) and amniotic fluid. MAS is present in 7.1% of full-term NICU infants (Talisman et al., 2022). The aspirated meconium can partially or completely block the infant’s airways, causing respiratory distress, lung irritation, and infection. Meconium also prevents the normal function of surfactant, which helps the infant’s lungs expand following delivery. It is not always clear why MAS occurs, but fetal distress during birth is a contributing factor.

MAS can range in severity from mild to life-threatening. More severe cases require extensive life support such as mechanical ventilation or ECMO. Most infants with uncomplicated MAS will recover without any long-term issues. However, those who are severely affected may develop chronic lung disease or neurological/developmental delays. Very severe cases of MAS may be fatal.

Neonatal Abstinence Syndrome / Neonatal Opioid Withdrawal Syndrome

Neonatal abstinence syndrome (NAS), commonly known as neonatal opioid withdrawal syndrome (NOWS), is a condition in which a newborn experiences withdrawal symptoms from a drug they were exposed to in utero. An infant can withdraw from prescribed maternal medications, such as antidepressants, opioids (e.g., heroin, codeine, tramadol, hydrocodone), or other types of legal or illegal drugs. Symptoms of NAS/NOWS include infant tremors, hypertonia, seizures, excessive fussiness/crying, poor oral intake, breathing problems, trouble sleeping, diarrhea, and fever. The onset and severity of withdrawal symptoms can depend on the type of drug used, frequency and duration of use, the infant’s GA, and more. NAS/NOWS can cause long-term consequences, including neurodevelopmental delays, behavior and learning problems, and speech and language delays. Treatment for NAS/NOWS may include nonpharmacological interventions (e.g., swaddling, skin-to-skin contact) and/or medications to treat withdrawal symptoms (Young et al., 2023).

Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a gastrointestinal disease that involves infection and inflammation that cause damage and the death of cells in the intestine. NEC occurs in 8.9% of extremely preterm neonates (Bell et al., 2022). NEC is most common in preterm infants and in full-term infants with other comorbidities, such as congenital heart disease. NEC may arise from issues with circulation and oxygenation. Infants who develop NEC, whether NEC is managed with medication or surgery, often have difficulty tolerating and/or absorbing certain milks or formulas.

Neonatal Hypoglycemia

Neonatal hypoglycemia occurs when the infant’s blood sugar levels cause symptoms or fall below the range considered safe. In a newborn infant, low blood sugar can cause problems such as tremors, cyanosis, temperature instability, and breathing and feeding problems. Infants are at risk for hypoglycemia if

• the birthing parent has gestational diabetes,
• they are SGA or LGA, or
• they had slower-than-expected growth in utero or are born preterm.

Hypoglycemia affects between 12% and 18% of full-term infants in the NICU (Mendoza & Lutz, 2022; Talisman et al., 2022). Infants born to diabetic mothers are at a higher risk for being LGA and for having IUGR, birth injuries such as HIE, respiratory distress, and other long-term complications. Treatment for hypoglycemia includes oral feeding of breast milk and/or formula. Some infants will require intravenous dextrose to support their blood sugar levels.

Neonatal Hypothermia

Neonatal hypothermia occurs when an infant’s core body temperature drops below 36.5 °C or 97.7 °F. Infants create their own body heat, but environmental factors and disorders may lower their body temperature. Infants who are SGA or born preterm are at a higher risk for hypothermia. This is due to immature skin development and decreased subcutaneous fat to insulate against the cold. Hypothermia may cause hypoglycemia, breathing difficulties, and jaundice. The main treatment for neonatal hypothermia is rewarming, which can be done under a radiant warmer or an incubator.

Neonatal Jaundice (Hyperbilirubinemia)

Neonatal jaundice—or hyperbilirubinemia—is the yellowing of skin and eyes due to excess bilirubin—the yellow pigment in an infant’s blood. Jaundice occurs because the infant’s liver is underdeveloped and cannot adequately break down the bilirubin and remove it from the blood. Hyperbilirubinemia can cause brain damage and seizures if not treated. Jaundice rates in full-term NICU infants range from 11% to 12% (Mendoza & Lutz, 2022; Talisman et al., 2022). Jaundice may result in lethargy and/or poor oral intake. An infant can have various types of jaundice:

• Physiologic jaundice—the most common and typical type of jaundice that occurs by the second or third day of life.
• Breastfeeding jaundice—occurs when an infant is not getting enough human milk during the first week of life due to feeding difficulties or a reduced milk supply.
• Human milk jaundice—occurs due to substances in human milk that prevent the breakdown of bilirubin when intake and weight gain are normal.
• Rh disease or ABO incompatibility—occurs when an infant has a different blood type than the birthing parent. This incompatibility results in hemolysis, or the breakdown of red blood cells resulting in excess bilirubin.

Omphalocele

With omphalocele, the abdominal wall fails to form, and the intestines and/or other abdominal organs extend and grow outside of the abdominal wall; the organs are covered in a thin, nearly transparent sac. The prognosis for an infant with an omphalocele largely depends on their size and the presence of other birth defects. More than half of infants born with omphalocele have other birth defects—including brain, spine, heart, gastrointestinal, or genitourinary problems.

Infants with an omphalocele require surgery after birth to fix the defect. The number of surgical procedures depends on the size of the omphalocele and which abdominal organs are herniated. Similar to infants born with gastroschisis, children born with an omphalocele may have feeding and/or swallowing impairments from necessary medical treatments and surgical interventions.

Patent Ductus Arteriosus

The ductus arteriosus connects the pulmonary artery and the aorta in fetal blood circulation. The pulmonary artery carries deoxygenated blood from the heart to the lungs, and the aorta carries oxygenated blood from the heart to the body. Before birth, the ductus arteriosus lets blood bypass the lungs as the fetus receives oxygenated blood through the placenta.

Patent ductus arteriosus (PDA) occurs when the opening between the aorta and the pulmonary artery does not close as it should after birth. This opening results in excess blood flow to the lungs. The infant may then experience respiratory problems such as tachypnea, respiratory distress, poor oral intake, lethargy, and slow weight gain.

If PDA does require surgical intervention, then best practices dictate that speech-language pathologists are made aware of possible damage to the recurrent laryngeal nerve and vocal fold paralysis.

Periventricular Leukomalacia

Periventricular leukomalacia (PVL) is an injury to the white matter around the fluid-filled ventricles of the brain. White matter transmits information between nerve cells, to the spinal cord, and from one part of the brain to another. PVL is a major cause of neurologic morbidity and occurs in 4.6% of extremely preterm infants (Bell et al., 2022; Volpe, 2001). The exact cause of PVL is unknown, but it is associated with IVH, infection of the uterus in pregnancy, and premature rupture of membranes in the pregnant parent. PVL can cause damage to the nerve pathways that control motor movements, resulting in muscles that are weak and tight, spastic, or resistant to movement. Infants with PVL are at a higher risk for cerebral palsy (Volpe, 2001). They may also have learning difficulties and other developmental delays.

Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a serious and life-threatening condition that happens when an infant’s fetal circulation does not adapt to extrauterine circulation. PPHN can result in the heart, brain, and other organs not receiving enough oxygen. PPHN most often occurs in full- or post-term infants following a difficult birth. PPHN can also occur in preterm infants.

Severe PPHN may require ECMO and/or nitric oxide. Mild cases of PPHN recover without long-lasting morbidity. However, PPHN is associated with significant long-term morbidity and neurodevelopmental impairments seen in approximately 25%–27% of infants who survive (Konduri et al., 2007).

Respiratory Distress Syndrome

Respiratory distress syndrome (RDS) occurs most commonly in preterm infants whose lungs are not fully developed. A premature infant’s lungs do not have enough surfactant to prevent alveolar collapse. Surfactant is a liquid made in the lungs that increases with gestational age. Infants with RDS may demonstrate tachypnea, perioral cyanosis, grunting, or retractions in the neck and chest. Between 41% and 47% of full-term infants admitted to the NICU also experience RDS (Mendoza & Lutz, 2022; Talisman et al., 2022).

Retinopathy of Prematurity

Retinopathy of prematurity (ROP) is a disease that happens when blood vessels grow abnormally in the retina of the eye. ROP may get better on its own, but more severe cases of ROP may progress quickly and cause blindness (National Eye Institute, 2023). Doctors describe ROP by zone, stage, and the presence or absence of disease. Among extremely preterm neonates, 55% have ROP, with incidence rates ranging from 30% at 28 weeks’ gestation to 93% at 22 weeks’ gestation (Bell et al., 2022).

Sepsis

Neonatal sepsis is a severe systemic response to an infection involving the bloodstream in infants less than 28 days old. Early-onset neonatal sepsis occurs within the first 72 hours of life. Late-onset neonatal sepsis develops after 3 days of life and affects approximately 20% of extremely preterm neonates (Bell et al., 2022). Infants can become septic later in the NICU stay due to bacterial infection, which is the most common cause of sepsis. Doctors treat sepsis with antibiotics, oxygen, medications, and fluids. Severe sepsis can lead to organ failure and even death.

Tracheoesophageal Fistula and Esophageal Atresia

Tracheoesophageal fistula (TEF) is an abnormal connection between the esophagus and the trachea, which allows liquid to pass into the trachea and airways. This can lead to lung infection and pneumonia.

TEF often co-occurs with esophageal atresia (EA), when the esophagus does not form properly and results in two segments: (a) Part of the esophagus connects to the larynx (proximal atresia), and (b) another part of the esophagus connects to the stomach (distal atresia). There is no connection between the proximal and distal ends. TEF/EA commonly occurs with comorbidities such as congenital heart defects and genetic syndromes (Friedmacher et al., 2017; Sulkowski et al., 2014). Surgery is required to fix TEF/EA, and infants with TEF/EA may have ongoing feeding difficulties and esophageal comorbidities, such as gastroesophageal reflux (Friedmacher et al., 2017; Maybee et al., 2023).

There are five types of TEF/EA:

1. isolated esophageal atresia
2. esophageal atresia with proximal tracheoesophageal fistula
3. esophageal atresia with distal tracheoesophageal fistula
4. esophageal atresia with proximal and distal tracheoesophageal fistula
5. isolated tracheoesophageal fistula

Transient Tachypnea of the Newborn

Transient tachypnea of the newborn (TTN) is a mild respiratory disorder that occurs in early- or late=preterm infants and typically lasts for a few days. TTN occurs in 3.9% of NICU-admitted infants and is due to slow absorption of fluid in the fetal lungs (March of Dimes National Perinatal Information Center Quality Analytic Services, 2011). Slow absorption makes oxygenation difficult and results in fast breathing (known as tachypnea), grunting sounds, nostril flaring, and retractions. Infants with TTN typically require respiratory support, such as high-flow nasal cannula or continuous positive airway pressure.

References

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Konduri, G. G., Vohr, B., Robertson, C., Sokol, G. M., Solimano, A., Singer, J., Ehrenkranz, R. A., Singhal, N., Wright, L. L., Van Meurs, K., Stork, E., Kirpalani, H., Peliowski, A., Johnson, Y., & Neonatal Inhaled Nitric Oxide Study Group. (2007). Early inhaled nitric oxide therapy for term and near-term newborn infants with hypoxic respiratory failure: Neurodevelopmental follow-up. The Journal of Pediatrics, 150(3), 235–240. https://doi.org/10.1016/j.jpeds.2006.11.065

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Mendoza, G. T., & Lutz, T. (2022). A review of term admissions to a neonatal intensive care unit—Are some more suited for a transitional unit? Journal of Neonatal Nursing, 29(3), 482–485. https://doi.org/10.1016/j.jnn.2022.09.004 

National Eye Institute. (2023, November 15). Retinopathy of prematurity. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinopathy-prematurity

O’Shea, T. M., Allred, E. N., Kuban, K. C. K., Hirtz, D., Specter, B., Durfee, S., Paneth, N., & Leviton, A. (2012). Intraventricular hemorrhage and developmental outcomes at 24 months of age in extremely preterm infants. Journal of Child Neurology, 27(1), 22–29. https://doi.org/10.1177/0883073811424462

Sharma, D., Sharma, P., & Shastri, S. (2016). Postnatal complications of intrauterine growth restriction. Journal of Neonatal Biology, 5(4), 232. https://www.walshmedicalmedia.com/open-access/postnatal-complications-of-intrauterine-growth-restriction-2167-0897-1000232.pdf [PDF]

Sulkowski, J. P., Cooper, J. N., Lopez, J. J., Jadcherla, Y., Cuenot, A., Mattei, P., Deans, K. J., & Minneci, P. C. (2014). Morbidity and mortality in patients with esophageal atresia. Surgery, 156(2), 483–491. https://doi.org/10.1016/j.surg.2014.03.016

Talisman, S., Guedalia, J., Farkash, R., Avitan, T., Srebnik, N., Kasirer, Y., Schimmel, M. S., Ghanem, D., Unger, R., & Grisaru Granovsky, S. (2022). NICU admission for term neonates in a large single-center population: A comprehensive assessment of risk factors using a tandem analysis approach. Journal of Clinical Medicine, 11(15), Article 4258. https://doi.org/10.3390/jcm11154258 

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