What is a newborn? The term refers to a baby during the first 28 days of life. This short window marks a critical period of adjustment, for both the infant and the parents. Newborns undergo rapid changes as they adapt to life outside the womb. Their bodies learn to breathe, regulate temperature, and process food independently for the first time.
Understanding what defines a newborn helps caregivers recognize normal development and spot potential concerns early. From physical features to feeding patterns, newborns display distinct characteristics that set them apart from older infants. This guide covers the key aspects of the newborn stage, including physical traits, care basics, common behaviors, and warning signs that require medical attention.
Key Takeaways
- A newborn is a baby during the first 28 days of life, a critical period of adjustment and vulnerability.
- Newborns display distinct physical features like soft spots on the skull, and may have skin conditions like jaundice that typically resolve naturally.
- Feeding a newborn requires 8–12 sessions daily, as their tiny stomachs hold only about a teaspoon at birth.
- Primitive reflexes like rooting, sucking, and the Moro reflex indicate healthy neurological development in newborns.
- Seek immediate medical attention if your newborn has a fever of 100.4°F or higher, refuses feedings, or shows signs of dehydration.
- Safe sleep practices are essential—always place newborns on their backs in a crib with a firm mattress and no loose bedding.
Defining the Newborn Stage
The newborn stage spans from birth through the first 28 days of life. Medical professionals use this specific timeframe because it represents a unique period of vulnerability and adaptation. After 28 days, a baby transitions into the infant stage, which continues until the first birthday.
During the newborn period, babies require close monitoring. Their immune systems are still developing, and they depend entirely on caregivers for survival. A newborn cannot hold up their head, roll over, or communicate beyond crying.
The World Health Organization defines newborns within this 28-day window for good reason. Most infant deaths occur during this period, making proper care and awareness essential. A newborn’s body systems, respiratory, digestive, and circulatory, are still maturing. They’re learning to function without the placenta’s support.
Premature babies may be classified as newborns for longer periods in terms of developmental milestones. A baby born at 34 weeks will behave differently than a full-term newborn, even at the same chronological age. Healthcare providers often use “corrected age” to assess preterm newborns’ development.
Physical Characteristics of Newborns
Newborns look quite different from the chubby babies seen in advertisements. Their appearance often surprises first-time parents.
Head and Face
A newborn’s head is large relative to their body, about one-quarter of their total length. The skull contains soft spots called fontanelles. These gaps between skull bones allow the head to pass through the birth canal and give the brain room to grow. The anterior fontanelle typically closes between 12 and 18 months.
Many newborns have misshapen heads after vaginal delivery. This is normal and resolves within a few days. Their faces may appear puffy, and their eyelids often swell.
Skin
Newborn skin varies in appearance. Many babies are born covered in vernix caseosa, a white, waxy substance that protected their skin in the womb. Lanugo, fine, downy hair, may cover a newborn’s shoulders, back, and forehead. Both typically disappear within the first weeks.
Skin color changes frequently in newborns. Hands and feet often appear bluish due to immature circulation. Jaundice, a yellowing of the skin and eyes, affects about 60% of newborns and usually resolves without treatment.
Size and Weight
The average full-term newborn weighs between 5.5 and 10 pounds and measures 19 to 21 inches long. Birth weight varies based on genetics, maternal health, and gestational age. Newborns typically lose 5-10% of their birth weight in the first week before regaining it by day 10-14.
Essential Newborn Care Basics
Caring for a newborn involves meeting their basic needs: feeding, sleeping, hygiene, and safety.
Feeding
Newborns eat frequently, 8 to 12 times per day for breastfed babies, or every 2-3 hours for formula-fed infants. Their stomachs are tiny. A one-day-old newborn’s stomach holds only about 5-7 milliliters (roughly a teaspoon). By day 10, capacity increases to about 45-60 milliliters.
Watch for hunger cues: rooting (turning toward touch on the cheek), sucking motions, and hand-to-mouth movements. Crying is a late hunger sign.
Sleep
Newborns sleep 14-17 hours daily, but never for long stretches. They wake every 2-4 hours to feed. Safe sleep practices matter greatly during this stage. Place newborns on their backs in a crib with a firm mattress and no loose bedding, pillows, or toys.
Diaper Changes and Bathing
Expect 6-8 wet diapers and 3-4 bowel movements daily once a newborn’s milk intake is established. Breastfed newborns may have looser, yellowish stools. Formula-fed babies typically have firmer, tan-colored stools.
Sponge baths work best until the umbilical cord stump falls off (usually 1-3 weeks). After that, gentle tub baths 2-3 times weekly are sufficient.
Common Newborn Behaviors and Reflexes
Newborns display fascinating automatic responses. These reflexes indicate healthy neurological development.
Primitive Reflexes
Rooting reflex: When something touches a newborn’s cheek, they turn toward it and open their mouth. This helps them find the breast or bottle.
Sucking reflex: Newborns automatically suck when something enters their mouth. This reflex is essential for feeding.
Moro reflex: Also called the startle reflex. When a newborn feels like they’re falling or hears a loud noise, they throw their arms out, then pull them back in. This reflex fades by 3-4 months.
Grasp reflex: Place a finger in a newborn’s palm, and they’ll grip it tightly. This reflex is so strong that newborns can briefly support their own weight.
Stepping reflex: Hold a newborn upright with feet touching a flat surface, and they’ll make stepping motions.
Normal Behaviors
Newborns cry 1-4 hours daily on average. Crying peaks around 6-8 weeks before decreasing. They hiccup, sneeze, and make grunting sounds frequently, all normal.
Newborn sleep cycles differ from adults. They spend more time in REM (active) sleep, which explains their frequent twitching, smiling, and eye movements while sleeping.
When to Seek Medical Attention
Most newborn quirks are harmless. But, some symptoms require immediate medical evaluation.
Emergency Warning Signs
Call a doctor or go to the emergency room if a newborn:
- Has a rectal temperature of 100.4°F (38°C) or higher
- Refuses multiple feedings in a row
- Shows signs of dehydration (fewer than 6 wet diapers daily, no tears when crying, sunken fontanelle)
- Has difficulty breathing, rapid breathing, or blue lips
- Appears unusually limp or unresponsive
- Develops a rash with fever
- Has persistent vomiting (not spit-up)
- Shows yellowing of skin spreading to arms, legs, or abdomen
When to Contact Your Pediatrician
Schedule a same-day appointment for:
- Excessive crying that can’t be soothed
- Eye discharge or redness
- Umbilical cord redness, discharge, or odor
- Constipation (no stool in 3+ days for formula-fed newborns)
- White patches in the mouth (possible thrush)
Newborns can deteriorate quickly, so trust your instincts. Parents often notice subtle changes before symptoms become obvious. If something feels wrong with your newborn, seek evaluation.
