Introduction

Neonatal medicine involves medical care for a wide variety of diseases and disorders in newborn infants, ranging from extremely small preterm babies at the edge of viability to healthy infants who are admitted to a typical newborn nursery.

Neonatology was recognized as a medical specialty in the 1960s and 1970s. Key advances over the years in neonatology include thermoregulation, intravenous (IV) nutrition, methods of mechanical ventilation, artificial surfactant, and antenatal glucocorticoids for mothers at risk of premature delivery.

Neonatal Definitions and Classifications

Infants are classified according to gestational age, birth weight, and growth status.

Gestational age

extremely preterm: ≤28 weeks
preterm: 28 weeks to <34 weeks
late preterm: 34 weeks to <37 weeks
early term: ≥37 weeks to <38 weeks
term: ≥39 weeks to <42 weeks
post-term: ≥42 weeks

Birth weight

extremely low birth weight (ELBW): <1000 grams
very low birth weight (VLBW): 1000 to <1500 grams
low birth weight (LBW): 1500 to <2500 grams

Growth status

small for gestational age (SGA): <10th percentile for gestational age
appropriate for gestational age (AGA): 10th to <90th percentile for gestational age
large for gestational age (LGA): ≥90th percentile for gestational age

Neonatal Intensive Care Units (NICUs)

Nurseries caring for infants are designated as levels I–IV. The goal of neonatal intensive care is to provide appropriate intensity of care while attempting to keep the infant close to home, especially prior to discharge. The American Academy of Pediatrics (AAP) set standards for levels of care in a 2012 policy statement and provided further detail in a 2023 article. The levels of care are defined as follows:

Level I nurseries provide basic newborn care to infants ≥35 weeks’ gestational age without the need for respiratory support.
Level II nurseries are subdivided into Level IIA and Level IIB:
- Level IIA nurseries can care for infants ≥32 weeks’ gestational age and ≥1500 grams who do not require respiratory support.
- Level IIB nurseries have the additional ability to care for infants requiring mechanical ventilation for <24 hours or continuous positive pressure ventilation.
Level III nurseries are the most specialized and are divided into the following categories:
- Level IIIA can care for infants >28 weeks’ gestational age and >1000 grams.
- Level IIIB can care for all infants of all gestational ages and have access to a full range of pediatric subspecialists, including surgical subspecialists.
Level IV (or IIIC) can provide extracorporeal membrane oxygenation (ECMO) services or cardiopulmonary bypass.

Infants of 22 to 23 Weeks’ Gestation

Infants that are born approaching the limits of viability (infants of 22–23 weeks’ gestation) have special considerations in terms of the management of all systems. Data are emerging about best practices in this population, which currently differ across centers.

The following topics in Neonatology are covered in this rotation guide:

Other relevant topics in Neonatology are covered in the following rotation guides:

Tanzeema Hossain, MD, is a neonatologist at Brigham and Women’s Hospital and an Assistant Professor of Pediatrics at Harvard Medical School. She is also the Director of Education for the BWH Neonatal Intensive Care Unit and Assistant Director of the STRATUS Center for Medical Simulation.

This rotation guide was developed by a collaborative team of contributors including:
Writer: Courtney Verscaj, MD and Kristyn Beam, MD
Peer Reviewers: Laurie Delatour, MD PhD; Andrew Parsons, MD; Ivor Asztalos MD, Atu Agawu MD, Barbara Chaiyachati MD
Section Expert: Tanzeema Hossain, MD
Senior Editor: Shannon Scott-Vernaglia, MD
Last updated: July 2024 by Courtney Verscaj, MD

Brief Case Presentations with Videos

Neonatal Care Videos in Clinical Medicine

PICC Placement in the Neonate

Umbilical Vascular Catheterization

Neonatal Circumcision

Suprapubic Bladder Aspiration

Catheterization of the Urethra in Girls