Almost everything difficult about a newborn comes from one fact: a few minutes ago they were
living underwater, and the entire circulation was arranged for it.
Hold that and most of neonatology follows. The tiers below map onto the three phases of a medical program
— the science, then the clinical reasoning, then what you will be expected to do with your own hands.
Read the one that fits and glance at the one above it.
Tier one
The transition, and why it is the whole subject
Phase 1 — the foundational years, and anything called Beginnings, Growth and Development
The fetal circulationThree shunts exist to bypass lungs that do not work yet: the ductus
venosus past the liver, the foramen ovale between the atria, and the ductus arteriosus from pulmonary artery
to aorta. Oxygenated blood arrives from the placenta, not the lungs. Learn this properly once and a great
deal else becomes obvious.
The first breathAir replaces fluid, oxygen floods the pulmonary vasculature, and pulmonary
vascular resistance falls sharply. Pulmonary blood flow rises, left atrial pressure exceeds right, and the
foramen ovale closes functionally. The duct constricts over hours to days, driven largely by rising oxygen
tension and falling prostaglandins.
Why that matters clinicallyAnything that keeps pulmonary resistance high — hypoxia,
acidosis, hypothermia, sepsis — can reverse the transition and push the circulation back towards the
fetal pattern. That is persistent pulmonary hypertension of the newborn, and it is transition failing.
SurfactantProduced by type II pneumocytes, rising sharply after about 34 weeks. It lowers
surface tension and stops alveoli collapsing at end-expiration. Its absence is respiratory distress syndrome,
and antenatal steroids work by accelerating its production.
HeatEnormous surface area to mass, thin skin, no shivering. Newborns generate heat from brown
adipose tissue by non-shivering thermogenesis — an expensive process that consumes oxygen and glucose
the baby may not have.
Glucose and bilirubinSmall glycogen stores and immature gluconeogenesis. And an immature
hepatic conjugating system, which is why physiological jaundice exists at all — and why jaundice in
the first 24 hours is never physiological.
The elegant bit. The ductus arteriosus is held open in fetal life by prostaglandin E2 from
the placenta and by low oxygen tension. Both disappear at birth, and it closes. Which is exactly why, in a
baby whose survival depends on that duct, we give prostaglandin back — and why giving high-flow oxygen
to such a baby is actively harmful. One piece of physiology, two bedside decisions.
If you take one thing: a newborn is not a small child having a hard time. They
are an organism completing the most abrupt physiological transition of their life, and most neonatal illness
is that transition going wrong.
Likely to be examined as: a diagram of the fetal circulation with the three shunts
labelled, a short answer on what closes the ductus arteriosus, or a viva on why a preterm infant develops
respiratory distress syndrome. Draw the circulation from memory until you can do it without thinking.
Tier two
Reading a newborn
Phase 2 — the clinical years, paediatric attachments, and the ICE
The Apgar scoreAppearance, Pulse, Grimace, Activity, Respiration, at one and five minutes.
It describes the baby's condition and the response to resuscitation. It does not guide resuscitation and it
does not predict outcome in an individual child — a point worth making if you are asked.
Delayed cord clampingAt least 60 seconds for a vigorous infant of 34 weeks or more; at least
30 seconds below 34 weeks. Both are weak recommendations, and, counter-intuitively, the preterm evidence is
the stronger of the two.
Saturations climb slowlyPreductal saturation — right hand — is expected around
60–70% at one minute and 70–90% at three, reaching the nineties by about ten minutes. A baby who
is pink at two minutes has usually been given too much oxygen.
Respiratory distressTachypnoea, recession, flaring, grunting. The differential is wider than
it looks: transient tachypnoea, respiratory distress syndrome, meconium aspiration, pneumonia, pneumothorax,
congenital diaphragmatic hernia, and cardiac disease masquerading as lung disease.
JaundiceIn the first 24 hours it is pathological until proven otherwise — think
haemolysis, and think sepsis. After that, plot the bilirubin on the age-specific chart rather than judging by
eye, and note that gestational age shifts the threshold.
Sepsis presents as nothingPoor feeding, temperature instability in either direction,
lethargy, irritability, mottling. Group B streptococcus and E. coli dominate early-onset disease.
A well-looking newborn with any of these gets a septic screen and antibiotics.
The duct-dependent babyCollapse at day two to fourteen as the duct closes: grey, poorly
perfused, weak femorals, differential saturations, lactic acidosis. Oxygen makes it worse. This is the
diagnosis not to miss in a baby who was discharged home well.
If you take one thing: in the newborn, the same handful of signs cover almost
every serious diagnosis. Which means the skill is not pattern recognition but discipline — screening for
the dangerous causes every time, because the presentation will not distinguish them for you.
Likely to be examined as: a newborn examination station, a data interpretation question
on a bilirubin chart or a blood gas, or a scenario asking you to justify a septic screen. You may be asked to
explain delayed cord clamping to a parent — practise saying it in plain words.
Tier three
What you will be expected to do
Phase 3 — the final years, the pre-internship term, and your first night covering a birth suite
Warm, dry, stimulateThe first thirty seconds, every time. Below 32 weeks the baby goes
straight into polyethylene wrap without being dried, on a thermal mattress, with a hat. Target
axillary temperature 36.5–37.5 °C, and hypothermia on arrival in the nursery is a preventable
harm you will be asked about.
Heart rate is the numberNot saturation, not colour. If the rate is below 100 with inadequate
breathing, ventilate. If it is below 60 after 30 seconds of effective ventilation, start
compressions at 3:1.
If the chest is not movingNothing downstream works until it is. Mask seal, Reposition the
airway, Suction, Open the mouth, Pressure up, Airway alternative. Compressions before effective ventilation
are simply an interruption.
Start in airTerm and near-term resuscitation begins in room air. Titrate to the saturation
targets rather than to how pink the baby looks.
The numbers to have written downAdrenaline 10–30 µg/kg intravenously; volume
10 mL/kg only if blood loss is suspected; dextrose 2 mL/kg of 10% for hypoglycaemia; endotracheal tube
2.5–3.5 mm depending on gestation. Umbilical venous access is faster than you expect.
Cooling has a six-hour windowModerate or severe encephalopathy at 35 weeks or more, started
within six hours, to 33–34 °C. The decision is clinical and the window does not reopen, so
telephone the retrieval service before you are certain. Passive cooling begins with turning the warmer
off.
Speak to the parentsThey are two metres away and they can hear everything. Say what you are
doing and why, use the baby's name if there is one, and afterwards sit down rather than standing. This is
assessed, and more importantly it is remembered.
If you take one thing: newborn resuscitation is overwhelmingly about
ventilation and about temperature. Almost every baby who needs help needs those two things
and nothing more, and the errors that matter are the ones that delay them.
Likely to be examined as: a newborn resuscitation scenario, a viva on the ANZCOR
algorithm, or a station on breaking difficult news to parents. In practice it will be examined at 2 am by
a midwife who has called you because something is not right.
Over to you
What is the thing about newborns that nobody explained to you properly — and that you had
to work out for yourself?
Students ask better questions than anyone else in the hospital, largely because you have not yet learnt
which ones you are supposed to already know the answer to. Send me the thing that confused you. If several
of you name the same thing, it becomes the next piece I write.