During pregnancy, babies receive 100% of their oxygen from their mother.
As she inhales, oxygen enters her bloodstream then flows to the placenta, and is transported to the baby through the umbilical cord.
Carbon dioxide (CO2) and waste products from the baby travel back through the cord to the placenta. From there they are transferred back into the maternal system to be disposed of.
Babies get everything they need for their growth and development through this amazing system.
But what about when your baby is born? When do babies take that first breath and how do they adapt to breathing for themselves? Let’s explore this more.
When do babies start breathing in the womb?
Babies don’t breathe their own oxygen when they’re in the womb. Instead, they receive it from their mother, via the placenta.
We call this fetal circulation, and the process can be described simply, like this:
- Oxygenated blood and nutrients from the mother are transferred, via the placenta, through the cord, to the baby
- Blood enters the baby through the umbilical vein and moves towards the liver. It passes through a shunt (or special opening) called the ductus venosus
- This allows a small amount to go to the liver, but the majority bypasses it, and goes into the inferior vena cava. This takes blood into the baby’s heart, which then pumps it to the brain and other parts of the body
- The baby’s lungs receive only a small amount of blood – just enough to keep the tissue healthy
- Blood, containing CO2 and waste products, is transported to the umbilical arteries and back to the placenta
- CO2 and waste are returned to the maternal system
- Oxygen and nutrients are exchanged between mother and baby, and the cycle begins again.
Baby’s first breath physiology
The process that happens at birth, when a baby switches from fetal circulation to breathing independently (newborn circulation) is complex but amazing.
The following information will help you understand what happens physically when a baby takes its first breath:
- At birth, stimuli such as changes in temperature and environment cause the baby to inhale sharply
- Air is drawn into the baby’s lungs
- The lungs expand and push amniotic fluid out of the alveoli (air sacs)
- This allows more oxygen-rich blood to flow into the lungs
- Pressure changes in the lungs and the heart cause special openings that existed for fetal circulation to shut permanently. This redirects blood flow to the lungs.
This process completes the successful conversion from fetal to newborn circulation. The baby’s muscles, organs, and brain are now oxygenated by the baby’s own system.
How long does it take for a baby to take its first breath?
Your baby takes the first breath usually within ten seconds of birth. These first few breaths, initiated by the newborn, are the most difficult.
Most full-term infants will gasp spontaneously within seconds of birth.
90-95% of newborns will complete this transformation without any help.
What stimulates a newborn’s first breath?
How do babies know when to take their first breath?
The reality is that babies, like all mammals, are primed for survival.
Taking the first breath is a primal reflex essential for keeping the baby alive and is triggered by the change in air temperature and environment.
- Only 5-10% of babies require basic stimulation, such as drying and rubbing, to initiate breaths
- 3-6% require basic resuscitation steps (bag and mask ventilation)
- Less than 1% of babies require advanced resuscitation (cardiac compressions or drugs).
For more information be sure to read How Do Babies Breathe During Labor?
Factors that initiate respiration in newborn
There are a number of factors that can aid or hinder your baby’s ability to take the first breath and establish respiration.
These factors include:
- Reduced oxygen levels. During birth, babies experience periods of lower oxygen levels, which allows carbon dioxide to build up. Babies are designed to cope with this for short periods, and it is important for the establishment of regular breaths. Reduced oxygen for extended periods (oxygen deprivation), however, leads to complications such as hypoxia, resulting in c-section.
- Labor vs no labor. Babies who don’t experience contractions (babies born by elective c-section) are more likely to have breathing problems after birth. They’re more likely to have fluid in their lungs, as labor contractions squeeze fluid from the air sacs in preparation for birth
- Induced vs spontaneous labor. Research suggests stress hormones such as adrenaline increase in the baby towards the end of pregnancy, before the start of labor, and just before birth. These hormones help the human fetus to transition to life outside the womb. When labor is induced, the baby misses out on these natural hormonal surges
- Mode of birth. Babies born vaginally are better equipped for these changes than babies born via c-section. During vaginal birth, the baby’s chest is compressed when squeezing through the birth canal. Lung compression squeezes out as much fluid as possible and then, after birth, the chest can expand fully. Babies born via c-section are squeezed to a much lesser degree, and are more likely to have fluid left in the lungs
- Medications in labor. Opiate analgesia or epidural anesthetics affect a newborn’s respiratory system. These medications can cause slow or ineffective breathing
- Sensory stimuli to the skin. Change in temperature, lack of amniotic fluid, exposure to the air, and tactile stimulation, all encourage a baby’s first breath
- Stimulation of senses. Babies are used to a warm, dark, snug, and safe environment, and are often born into one that’s completely opposite. They suddenly feel exposed – to bright lights, loud noises, and new smells. This stimulation of the senses can also trigger a baby’s first breath
- Meconium. This is sometimes released by the baby during labor. If inhaled, it poses a problem – a condition known as meconium aspiration syndrome and makes breathing more difficult
- Gestation. When babies are born affects their ability to establish breathing on their own. Preterm babies find it harder to make the transition smoothly. Their lungs are less well developed, compared with full-term babies.
Why do preterm babies have trouble breathing?
Preterm babies haven’t had as much time produce surfactant – a substance that keeps the air sacs in the lungs from sticking together when exhaling. Surfactant also helps the lungs to inflate and prevents them collapsing in on themselves, which makes breathing harder.
Some babies born at this point, however, will still struggle to maintain breathing for themselves and might require respiratory support from a breathing machine or ventilator.
The lungs aren’t considered mature until around 36 weeks. Generally the longer the gestation, the better it is for the health of newborn babies, as they are better equipped to deal with their new world.
Why is the first breath of a newborn the most difficult?
The first breath immediately after birth is mechanically the most difficult for a newborn because it’s the first time the lungs are being used.
Within a couple of breaths, the baby’s lungs will inflate. They become filled with air, and push out the fluid inside them.
Only after this is done can the lungs effectively take in oxygen and eliminate carbon dioxide.
Imagine blowing up a balloon for the first time. The balloon is like the newborn’s lungs. Your first attempt to blow up the balloon takes a lot of effort, but once you get started it becomes easier. The next time you blow it up, it’s easier still.
The process is similar for the baby. Once their lungs have begun working, the muscles involved in breathing don’t have to work so hard to keep them inflated.
Can a baby breathe with the umbilical cord attached?
Most babies will breathe spontaneously immediately after birth, even when they are still connected to the cord.
Because blood is still flowing to the placenta, babies will still receive oxygen from their mother, even when breathing for themselves.
This will continue until the cord naturally stops pulsing. This is known as delayed cord clamping. Doctors usually clamp and cut the cord after three minutes but you can request to leave it for longer.
Ways to support babies in their newborn transitions
The first moments after birth are incredibly precious as you meet your baby for the first time. While your newborn is adjusting to life outside the womb, you can support this transition by:
- Skin to skin. This helps regulate your baby’s heart rate, breathing, and temperature, whilst also providing much-needed reassurance and familiarity. If mums aren’t feeling up to providing that initial skin to skin, dads can have skin to skin too
- An early feed. Feeding within the first couple of hours of life allows your baby to conserve precious energy reserves
- Keeping baby warm. Similarly, keeping your newborn nice and cozy will prevent a loss of energy from trying to regulate body temperature.
The first hour after birth should always be about you and your baby getting to know each other and helping your baby make this incredible transition.
Find out more in 7 Huge Benefits of An Undisturbed First Hour After Birth.