Highlights
- The first week is a key stage of adaptation to the outside world
- Most skin changes are part of normal physiology
- Primitive reflexes support the baby’s survival
- Frequent feeding and close contact with the mother support breastfeeding
- Sleep may reach up to 19 hours per day
In This Article
- General newborn adaptation
- Physiology of the first week
- Newborn thermoregulation
- Primitive reflexes
- What a baby can do
- Feeding and spit-ups
- Sleep
- Taste and smell
- The newborn adjustment period
General Newborn Adaptation
The first week of life is a period of intense adaptation to life outside the mother’s body. The baby’s organism rapidly reorganizes, innate survival mechanisms are activated, and the mother becomes the main source of safety, warmth, and comfort.
A baby is considered a newborn during the first 28 days of life; however, the very first week is the most intensive in terms of physiological and behavioral changes. After nine months of a protected intrauterine environment, the baby adapts to open space, a new rhythm of life, and a much larger world. Through her voice, scent, touch, and care, the mother helps the baby adapt gently and safely.
Physiology of the First Week
In the first days of life, a newborn’s skin may change noticeably, which often causes concern for parents.
Physiological jaundice may appear on days 2–4 of life as a temporary increase in indirect bilirubin. This is a transient condition that resolves on its own and does not require treatment.
Other possible skin changes include toxic erythema of the newborn and infant acne. These conditions are not related to the mother’s diet and do not require medication.
Newborn Thermoregulation
A newborn’s thermoregulation system is still immature. The baby can easily overheat or become chilled. Because newborns do not sweat yet, children under one year should not be taken to saunas or steam baths, and clothing and outdoor conditions should be chosen carefully.
Primitive Reflexes
Primitive (innate) reflexes are automatic responses present at birth. They allow the newborn to survive during the first weeks of life, when voluntary control of movements has not yet developed.
As the nervous system matures, these reflexes gradually weaken and disappear, giving way to purposeful, voluntary movements. Their presence, symmetry, and timely fading are important signs of healthy neurological development.
The main primitive reflexes observed during the first week of life include:
Sucking reflex — when the breast, nipple, or a finger touches the baby’s mouth, the infant begins rhythmic sucking movements. This reflex ensures nutrition and also has a calming effect.
Rooting reflex — when the baby’s cheek or the corner of the mouth is gently stroked, the infant turns the head toward the stimulus and opens the mouth, helping locate the source of food.
Protective reflex — when placed on the stomach, the baby reflexively turns the head to the side, allowing free breathing.
Grasp reflex — when a finger is placed in the baby’s palm, the infant tightly grasps it. This reflex prepares the hands for future purposeful use.
Proboscis reflex — a brief touch to the lips causes the baby to protrude the lips forward, supporting sucking and swallowing movements.
Support and automatic stepping reflex — when held upright with the feet touching a surface, the baby makes step-like movements. This does not indicate readiness to walk and disappears within the first months.
Moro (startle) reflex — triggered by a sudden sound or movement, the baby spreads the arms outward and then brings them back toward the body.
Babinski reflex — stroking the outer edge of the foot causes the toes to fan outward. This is normal in infants and disappears as the nervous system matures.
Asymmetrical tonic neck reflex — when the baby’s head is turned to one side, the arm on that side extends while the opposite arm bends, contributing to early coordination.
Galant and Perez reflexes — responses involving the trunk and spine when the back is stimulated; they normally fade during the first months of life.
The presence of these reflexes during the first week of life is normal. What matters is not how strong the reaction is, but whether it is symmetrical and appropriate for the baby’s age.
What a Baby Can Do
- Moves arms and legs chaotically
- Adapts to open space
- Begins to recognize the mother’s voice
Feeding and Spit-Ups
In the first days of life, a baby may lose up to 10% of birth weight. This is a normal physiological process.
- Breast milk is the optimal source of nutrition
- Feeding on demand is recommended
- Feeding frequency may reach every hour
Spit-ups are common in the first months of life. A normal volume during the first week is about one tablespoon. If the volume approaches that of a full feeding, medical attention is required.
Sleep
- May sleep up to 18–19 hours per day
- Is awake only about 15–20% of the time
Taste and Smell
- Newborns have more taste receptors than adults
- They can distinguish sweet and bitter tastes
- Sensitivity to salty taste develops closer to 5 months
Taste preferences begin forming before birth and are influenced by the mother’s diet. From birth, babies respond actively to smells, especially the scent of their mother’s milk.
The Newborn Adjustment Period
The mother is the baby’s main point of reference in the new world. Her voice, scent, and warmth help the baby feel safe. Frequent skin-to-skin contact reduces stress, supports breastfeeding, and strengthens the emotio
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