First breath
One of the most significant biological changes after birth is the baby’s first breath. As the child emerges from the womb and encounters the outside air, their lungs expand, and they take their first breaths independently. Previously, with the baby oxygenated in utero, the lungs are quite densely packed and largely unused.
Clearing of airways
As the baby takes their first breaths, any remaining amniotic fluid or mucus in their airways is usually cleared out, helping establish clear and unobstructed breathing. This is a key moment for medical staff in attendance, who are well trained to spot the signs of obstructed air passages before asphyxiation sets in.
Circulation changes
With the cutting of the umbilical cord, the baby’s circulatory system undergoes a major shift. Instead of the flow of nutrient-rich blood being drawn from the placenta, it instead circulates to the lungs, and the baby’s heart starts pumping blood to oxygenate the body independently.
Heart rate stabilization
Immediately after birth, the baby’s heart rate adjusts to regulate blood flow and oxygenation throughout the body. It may initially be rapid as the baby’s organs and muscles oxygenate but typically stabilizes within a few minutes. This is why babies are initially born a dark red or purple color, which then fades within the first day.
Temperature regulation
As babies transition from the warm environment of the womb to the outside world, their bodies begin to regulate their own temperature. Skin-to-skin contact with the parent helps maintain the baby’s body temperature. It also serves to relax the baby as these many biological processes take effect.
Colostrum production
Within the first few minutes after birth, and no earlier, the mother’s body begins producing colostrum, colloquially known as early breast milk. Colostrum is rich in antibodies and essential nutrients, providing the baby with initial nourishment and immune support, which babies seek less than an hour after birth.
Contraction of the umbilical vessels
After the umbilical cord is clamped and cut, the blood vessels within the cord constrict, helping to prevent excess bleeding and promote the transition to independent circulation. However, it takes 10-14 days for the umbilical cord to detach entirely; in some cases, it can take as long as 21 days.
Glucose regulation
The baby’s body starts regulating blood glucose levels independently after birth. The baby’s liver begins to produce glucose and manages its levels to meet the energy needs of the body. In a healthy baby, it only takes two to three days for glucose production to rise to a level that will be sustained into adulthood.
Reflexes
Amazingly, various reflexes are observed shortly after birth, such as the rooting reflex (turning towards touch on the cheek) and the sucking reflex (initiating sucking motions when something touches the roof of the mouth). These reflexes, entirely unnecessary within the carefully managed system of the womb, aid in feeding and survival instincts.
Hormonal changes
Birth triggers various hormonal changes in the baby’s body. The stress of labor and delivery stimulates the release of hormones such as cortisol and adrenaline, which help the baby adapt to the new environment by increasing alertness, initiating lung expansion, and preparing the body for independent functioning.
