Preterm births

Reading time: 4 min

The first minutes of life are extremely important, so much so that the first minute is known as the golden minute.

The foetus's circulation and way of receiving nutrients are very different from that of the newborn.

The placenta provides the foetus with oxygen and food The foetus's lungs are full of liquid and still not responsible for the exchange of oxygen and gases, and the alimentary canal is not the main nutritional pathway.

When leaving its mother's womb, and after the umbilical cord has been cut, vital changes take place that must occur in a harmonious way.

The lungs have to expel the liquid that has been inside them and leave space for air to go in, so that breathing is effective. The blood, of which only 10% was reaching the lungs, now has to get to them in order to become oxygenated. And the alimentary canal has to prepare for the absorption of nutrients.

In a full-term newborn, all these changes usually take place spontaneously. After a premature birth it is normal for the neonatologist to manipulate the newborn to facilitate the transition or stabilise the baby. The newborn may need help to start or maintain effective breathing. It is not infrequent for preterm babies to be transferred to the neonatal intensive care unit (NICU) with some type of respiratory support.

Baby in an incubator

Preterm babies born at 34 weeks or less are moved, in an incubator, from the delivery room to the neonatal unit. Those born at 35 weeks or later may stay with their mothers as long as they do not have any other pathology.

Once in the neonatal unit, the healthcare staff transfer the newborn from the transport incubator to an incubator or radiant warmer. This provides the correct temperature and humidity conditions so the baby can maintain its body temperature between 36.5 and 37ºC. Due primarily to the immaturity of their skin and lack of fatty tissue, preterm babies have difficulty regulating their temperature and they cool down easily. This increases their energy consumption and can aggravate many pathologies.

The cardiorespiratory constants are recorded:

High heart rate o blood pressure

Heart rate. Newborns have a higher heart rate than an older child or adult, and this tends to be higher the fewer the weeks of gestation the neonate has had. During the first days of life, the heart rate of a preterm baby ranges from 120 to 150 beats per minute.

Respiratory sounds or lung whistles

Breathing rate is also higher the fewer the weeks of gestation the neonate has had. Preterm babies usually breathe 50-60 times a minute, and this frequency increases when they have respiratory problems. Due to the immaturity of the respiratory system and central nervous system, preterm babies can present a fluctuating breathing rate, alternating periods of rapid breathing (tachypnoea) with others of slow, shallow breathing (bradypnoea). They can have respiratory pauses (apnoeas), which are usually short, and may be accompanied by slowed heart rate (bradycardia) and decreased oxygen saturation (desaturation). They tend to recover on their own or with mild tactile stimulation, but on other occasions they need stimulating or resuscitating by healthcare staff.

Measurement of finger oxygen saturation

Oxygen saturation in the blood (SaO2) reflects the quantity of oxygen carried by the haemoglobin in the blood with the purpose of reaching the tissues. Normal values in preterm babies oscillate between 92% and 100%.

Increased blood pressure

Arterial tension is the force the blood exerts on the artery walls whenever the heart beats. If the arterial tension is low, as can happen in seriously ill patients, it may be necessary to administer intravenous fluids and/or complex medication to standardise it.

In addition to monitoring, it is probable that preterm inpatients will need other devices:

Man with respiratory support

Nasal or orogastric cannula (a tube that is inserted through the nose or mouth and reaches the stomach) where food is administered, since, due to their immaturity, it is very difficult for preterm babies of less than 32 or 33 weeks to feed themselves through breast or bottle feeding.

Premature baby with a feeding tube in the nose

Central or peripheral venous catheters: through which parenteral nutrition is administered to the smallest and sickest, in addition to antibiotics or other medicines.

Insulin pump

Infusion pumps for the slow administration of medicines or food.

Baby connected to a vent in an incubator

Respiratory support devices. Some newborns with respiratory failure only need non-invasive ventilation (high flow, continuous positive airway pressure (CPAP) or biphasic positive airway pressure (BiPAP)). Nevertheless, if they do not maintain regular breathing, or their lungs do not perform gas exchange correctly, they often require invasive ventilation using more complex devices. In these situations it is necessary to intubate the patient.

Substantiated information by:

Ana Herranz Barbero
Erika Sánchez Ortíz
Maria Teresa Cobo Cobo
Marta Arnal Ahulló
Mª Dolors Salvia Roiges

Published: 20 February 2018
Updated: 20 February 2018

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.


Receive the latest updates related to this content.

Thank you for subscribing!

If this is the first time you subscribe you will receive a confirmation email, check your inbox

An error occurred and we were unable to send your data, please try again later.