The Newborn: Profile, Appearance and Adjustments

Your first hours with a newborn are about knowing normal cold, so the abnormal jumps out. Weight, length, head circumference, color, temperature, heart rate, and respirations all shift on a predictable timeline in the first minutes to hours of life. Plot them, watch the transition, and flag what falls outside the expected range.

Profile of the Newborn

Newborns vary in size and temperament; some are short and fat, some long and thin, some placid, some loud. Weight tracks race, genetics, and nutrition. Plot weight, length, and head circumference on a neonatal graph to judge whether they are appropriate for gestational age and to catch disproportion.

In the United States, the average birth weight is 3.4 kg or 7.5 lbs for a mature female and 3.5 kg or 7.7 lbs for a mature male. Across all races the normal weight is 2.5 kg or 5.5 lbs. The newborn loses 5% to 10% of birth weight in the first few days, holds steady for 1 day, then gains rapidly, and should gain 2 lbs per month for the first six months.

Average birth length is 53 cm or 20.9 inches for mature females and 54 cm or 21.3 inches for mature males. Head circumference in a mature newborn is 34 to 35 cm, measured with a tape across the center of the forehead and around the most prominent part of the posterior head. Chest circumference is 2 cm less than head circumference, measured at the nipple line.

Vital Statistics and Vital Signs

Parameter	Average
Weight	6.5 to 7.5 lbs (2.9 kg to 3.4 kg)
Length	50 cm (20 in)
Head circumference	33 to 35 cm (13 to 13.7 in)
Chest circumference	31 to 33 cm or 2cm less than head circumference
Abdominal circumference	31 to 33 cm

Adjustment to Extrauterine Life

Color in the first 15 to 30 minutes is acrocyanotic; after 2 to 6 hours, quick color changes occur with movement or crying. Temperature in the first 15 to 30 minutes falls from the intrauterine 100.6°F or 38.1°C, then stabilizes at 37.6°C after 2 to 6 hours. Heart rate runs as high as 180 BPM in the first 15 to 30 minutes, with wide swings on activity, then slows to 120-140 BPM. Respirations are irregular for the first few minutes, slow to 30-60 breaths per minute after 30 minutes, and turn irregular again only with activity. The newborn is alert in the first 15 to 30 minutes, then alternates sleep and wake phases. Just after birth it responds vigorously to stimulation, becomes hard to arouse during the resting period, and is responsive again 2 to 6 hours after birth. Bowel sounds appear after the first 15 minutes and persist.

Appearance of the Newborn

A higher red blood cell concentration and less subcutaneous fat give newborns a ruddy complexion that fades over the first month. A pale, cyanotic newborn may have poor central nervous system control; a gray newborn may have infection. Acrocyanosis (bluish hands, feet, and lips) is normal, but central cyanosis signals decreased oxygenation and is a concern.

Jaundice appears on the second or third day from the breakdown of fetal red blood cells; early feeding speeds feces through the intestine, blocks bilirubin reabsorption from the bowel, and can lessen physiologic jaundice. Pallor signals anemia, so watch closely for blood in stool or vomitus. The harlequin sign, red on the dependent side and pale on the upper side when lying on one side, has no clinical significance.

Vernix caseosa, the white cream-cheese-like coating, washes away in the first bath; never rub hard, it comes off gradually. Lanugo, the fine downy hair over shoulders, arms, and back, rubs away against bedding and clothing. Milia, white pinpoint papules usually on the cheek or bridge of the nose, disappear by 2 to 4 weeks of age.

The fontanelles are the soft spots where the skull bones join. The anterior fontanelle sits between the two parietal and two frontal bones, is diamond-shaped, and normally closes at 12 to 18 months. The posterior fontanelle sits at the junction of the parietal bones and the occipital bone, is triangular, and closes by the end of the second month. Newborns cry tearlessly until three months of age, when the lacrimal ducts mature.

Birthmarks include hemangiomas (vascular tumors of the skin), nevus flammeus (muscular purple or dark red lesions, usually on the face and thighs), strawberry hemangiomas (elevated areas of immature capillaries and endothelial cells), cavernous hemangiomas (dilated vascular spaces), Mongolian spots (slate-gray patches of pigment cells across the sacrum or buttocks), and forceps marks (circular or linear contusions matching the forceps blade on the cheeks).

Permanent eye color appears in the 3rd to 12th month. The external ear is not fully formed; the top of the ear should sit on a line drawn from the inner to the outer canthus and back across the side of the head. The nose looks large for the face, but the rest of the face outgrows it. The mouth should open evenly when the newborn cries.

Normal Pediatric Developmental Milestones

Most development happens in the early years, and parents lean on you for answers. Know the normal milestones cold so you can separate ordinary variation from pathology. First word, first smile, first roll-over: children tick these off as they play, speak, move, and learn. They develop at their own pace, but milestones mark the changes you should expect as the child ages.

General Principles of Developmental Milestones

Periodically assess four key domains: motor development, language development, problem-solving, and psychosocial skills. Development is orderly and predictable, proceeding head to toe and proximal to distal. Reactions move from general to specific and goal-directed, and children gain independence from early total dependence. Both intrinsic factors (physical traits, health, temperament, genetics) and extrinsic factors (family personalities, economic status, learning experiences, culture) shape development.

Domain 1: Normal Motor Development

Assess motor milestones by history and observation. Gross motor evaluation relies on neuromaturational markers like primitive reflexes and postural reactions. The Moro reflex is a primitive reflex present at birth that disappears between 3 and 6 months; stronger, more sustained primitive reflexes raise concern for CNS injury. The parachute reaction is an acquired postural reaction that orients the body in space through visual, proprioceptive, and vestibular adjustment by cerebral and cerebellar structures; delayed postural reactions can signal CNS damage. Fine motor skills use the small muscles of the hands, progressing from proximal to distal control as balance in sitting and moving improves.

Gross Motor Milestones
Age	Milestone
Birth	Turns head side to side
2 months	Lifts head when lying prone Head lags when pulled from supine position
4 months	Lifts head when lying prone Head lags when pulled from a supine position
6 months	Sits alone Leads with the head when pulled from a supine position
9 months	Rakes objects with the whole hand Transfers object from hand to hand
12 months	Walks
Fine Motor Milestones
Birth	Keeps hands tightly fisted
3-4 months	Brings hands together to the midline and then to the mouth
4-5 months	Reaches for objects
6-7 months	Uses immature pincer (ability to hold a small object between thumb and index finger)
9 months	Uses mature pincer (ability to hold a small object between thumb and the index finger)
12 months	Uses mature pincer (ability to hold small object between thumb and the index finger)

Red flags in motor development: persistent fisting beyond 3 months (neuromotor problems); early rolling over, early pulling to stand instead of sitting, and persistent toe walking (possible spasticity); and early hand dominance before 18 months (possible weakness of the opposite upper extremity from hemiparesis).

Domain 2: Normal Language Development

Language is the single best indicator of intellectual potential and the ability to communicate with symbols. It is often confused with speech, which is the vocal expression of language. This domain shows the most delays. A child usually understands about 10 times as many words (receptive language) as they can speak (expressive language). The first two years of life are the prime window for language acquisition.

Age	Milestone
Birth	Two-word telegraphic sentences (e.g. Mommy come) 25-50% of child’s speech should be intelligible
2-3 months	Cooing (runs of vowels), musical sounds (e.g. ooh-ooh, aah-aah)
6 months	Babbling (mixing vowels with mixed consonants) [e.g. ba-ba-ba ]
9-12 months	Jargoning (e.g. babbling with mixed consonants, inflection, and cadence) Begins using mama, dada (nonspecific)
12 months	1-3 words, mama and dada (specific)
18 months	20-50 words Beginning to use two-word phrases
2 years	Two-word telegraphic sentences (e.g. Mommy come) 25-50% of a child’s speech should be intelligible
3 years	Three-word sentences More than 75% of the child’s speech should be intelligible

Domain 3: Cognitive Development

Cognition covers thinking, memory, learning, and problem-solving. Estimate infant intelligence from problem-solving and language milestones; gross motor skills correlate poorly with cognitive potential.

Age	Concept
9 months	Object permanence (people and objects continue to exist even when an infant cannot see them). This ability to maintain an image of a person is the reason why separation anxiety (6-18 months) develops when a loved one leaves the room.
9-15 months	Cause and effect (understanding which actions cause certain results).
1-3 years	Magical thinking

Domain 4: Social Development

Social development is the ability to interact with people and the environment, shaped by culture and surroundings.

Age	Concept
12-36 months	Attachment (bonding with a primary caregiver begins at birth and empathy development is critical during this period).
15 months	A sense of self and independence (process of separation and individuation begins).
12-24 months	Social play (exhibit parallel play during the first 2 years of life).

Know normal development and its acceptable variations, and you can recognize pathologic patterns and delays early, then refer children who would benefit from early intervention programs.