The newborn stage lasts four weeks, or 28 days. This period, called the neonatal period in medical terms, begins at birth and ends when your baby reaches one month old. While four weeks sounds brief, it’s one of the most rapid periods of change your baby will go through, with major shifts in feeding, sleep, reflexes, and physical appearance happening week by week.
What Happens During the Four Weeks
Your newborn arrives with a set of built-in reflexes that drive survival during this stage. The rooting reflex, which causes your baby to turn toward anything that touches their cheek, is fully active at birth and starts to fade after the first month. The Moro reflex, that startled arms-out response when your baby feels unsupported, sticks around longer, lasting up to about six months. The grasping reflex, where your baby curls their fingers tightly around anything placed in their palm, follows a similar timeline. These reflexes are not learned behaviors. They developed in the womb and serve as early signs that your baby’s nervous system is working properly.
Vision is extremely limited during this stage. Your newborn can focus on objects roughly 8 to 12 inches away, which happens to be about the distance between your face and theirs during feeding. Anything beyond that range appears blurry. High-contrast patterns (black and white) are easier for them to see than colors during these first weeks.
Weight Loss and Recovery
Almost all newborns lose weight in the first few days after birth. A loss of 7 to 10 percent of birth weight is normal and happens because babies shed extra fluid they carried in the womb. A baby born at 8 pounds might drop to around 7 pounds 3 ounces before the trend reverses. Full-term babies typically regain their birth weight within 7 to 10 days. Premature babies take longer, usually 10 to 15 days or more.
This weight recovery is one of the first things your pediatrician tracks. If your baby hasn’t returned to birth weight by two weeks, it can signal a feeding issue that needs attention.
How Feeding Changes Week by Week
Your newborn’s stomach grows dramatically across the four-week period. On day one, it holds about 5 to 7 milliliters, roughly one teaspoon. By day three, capacity triples to about 22 to 27 milliliters. At one week, your baby can take in 1.5 to 2 ounces per feeding. By the end of the newborn stage at one month, stomach capacity reaches 3 to 5 ounces per feeding.
This rapid increase explains why feeding patterns shift so much during the first month. In the earliest days, your baby needs to eat very frequently, sometimes every one to two hours, because each feeding is so small. As stomach capacity grows, feedings gradually space out, though “gradually” is the key word. Most newborns still feed 8 to 12 times per day throughout the entire four-week period.
Sleep in the Newborn Stage
Newborns sleep about 16 hours per day, split roughly in half between daytime and nighttime. That sounds like a lot, but it rarely feels that way for parents because the sleep comes in short, irregular stretches. About half of a newborn’s sleep time is spent in REM sleep, a lighter, more active sleep stage. You’ll notice your baby twitching, making faces, or moving their eyes beneath closed lids. This is normal and plays a role in brain development.
Newborns have no circadian rhythm yet. They don’t distinguish between day and night, which is why they wake at all hours. This begins to shift toward the end of the newborn stage and into the second month, but consistent day-night sleep patterns won’t emerge for several more weeks.
Physical Milestones to Expect
One of the most visible changes during the newborn stage is the umbilical cord stump drying out and falling off. This typically happens about two weeks after birth, though it can take anywhere from one to three weeks. The stump gradually shrinks, darkens, and detaches on its own. If it hasn’t fallen off by three weeks, it’s worth mentioning at your next pediatric visit.
Your baby’s head shape may also change during this period. Babies born vaginally often have a slightly elongated or cone-shaped head from the birth canal, which rounds out within the first week or two. Skin changes are common too. Many newborns develop small white bumps on their nose and cheeks, blotchy red patches, or flaky peeling skin, all of which resolve on their own within the first month.
Wellness Visits During This Period
Your baby will have their first pediatric checkup within the first week of life, typically between 3 and 5 days old. This visit focuses on weight (checking for that expected initial loss), feeding, jaundice screening, and overall health. The next visit comes at one month old, right at the boundary of the newborn stage. At two months, your baby enters the infant stage and receives their first round of vaccinations.
These early visits are spaced closely together because so much changes in such a short window. Weight gain, feeding patterns, and reflexes all provide a snapshot of how your baby’s development is tracking during the newborn period.
Newborn vs. Infant: Where the Line Falls
The newborn stage ends at four weeks, but the transition isn’t dramatic. Your baby won’t suddenly behave differently on day 29. The four-week cutoff is a medical distinction that reflects the unique vulnerabilities of the earliest days: higher infection risk, rapid physiological adjustment to life outside the womb, and the critical establishment of feeding. After four weeks, your baby is medically classified as an infant, a term that applies through the first year of life.
In practical terms, many of the patterns that define the newborn stage, like frequent night waking and cluster feeding, continue well into the second and third months. But by the end of those first four weeks, your baby’s body has made its most fundamental adjustments: regaining birth weight, shedding the umbilical cord stump, and beginning to develop the visual and neurological foundations that support the faster-paced milestones ahead.