Background

After birth, there are several physiological changes that occur that allow neonates to survive postnatal life.

Antenatally:

– Whilst the baby is in the uterus, the lungs are filled with fluid

– The blood vessels that supply/drain the lungs are constricted (giving a high pulmonary vascular resistance)

– Most blood from the right side of the heart bypasses the lungs via the ductus arteriosus and the foramen Ovale

Perinatally:

– Shortly before and during labour, lung liquid production is reduced

– During descent through the birth canal, the infant’s chest is squeezed, draining some lung liquid

– Multiple stimuli initiate breathing, including the cold temperature and a surge in adrenaline levels

– The high catecholamine levels also stimulate reabsorption of alveolar fluid

– Once the infant breathes, most of the remaining lung fluid is absorbed into the pulmonary circulation

– On average, the first breath occurs 6s after delivery and regular breathing is established 30s after delivery

Post-Delivery

When a baby is delivered, there are essential procedures to conduct:

i) Cord clamping:

– Cord clamping is delayed in term infants (typically by 2-5 minutes)

– This is because it increases circulating volume and reduces chances of anaemia later

ii) Assessment:

– Neonates are assessed using the APGAR scoring system:

– This is used to describe a baby’s condition at 1 minute, 5 minutes and 10 minutes after delivery

– It is also done at 5-minute intervals thereafter (if the infant’s condition remains poor)

– If the baby’s condition is not good, immediately dry the baby and start timing with a clock

Each of 5 components is given a score from 0-2 and these are added together

– Good = 7-10                          

– Moderately depressed = 4-6                     

– Severely depressed = 0-3

iii) Vitamin K injection:

This is given to reduce the chances of neonatal bleeding

iv) Newborn hearing screening:

– The is an otoacoustic emission test which is performed on all babies in UK

– Abnormal results is followed up by a referral to a paediatric audiologist

v) Pulse oximetry screening:

– This is performed in some hospitals in the UK

– O₂ saturations measured in the first 24hrs of life to identify duct-dependent congenital heart disease

– If abnormally low or large difference –> needs medical review and echocardiogram

Newborn blood spot screening

A heel prick is taken on days 5-7 of life and used to screen for various conditions (1B, 2C’s and 1D)

B: Blood disorders

–> Sickle cell anaemia, thalassemia

C: Congenital hypothyroidism

C: Cystic fibrosis

D: 6 Metabolic Disorders:

– Phenylketonuria

– MCADD

– Maple syrup urine disease (MSUD)

– Isovaleric acidaemia (IVA)

– Glutaric aciduria type 1 (GA1)

– Homocystinuria (HCU)