psychomotor and physical development of infant

The physical growth of an infant and the effect of mental activity on motor skills. It is important that all concerned with the care of the newborn through infancy have guidelines for comparing the growth and development of an individual with normal standards. Certain activities of infants serve as general indicators of normal psychomotor development. The average ages for certain of these activities are shown in the accompanying table. See: table; arousal level

Appearance and loss of certain reflexes and reactions: The Moro reflex is present at birth and disappears by 3 to 6 months; the stepping and placing reflexes are present at birth and are no longer obtainable by 6 weeks; the tonic neck reflex is usually present at 2 months and is gone by 6 months; neck righting appears at 4 to 6 months and is gone by 24 months; the parachute reaction is present at 9 months and persists; sucking and rooting are present at birth and are usually gone by 4 months if tested while awake and by 7 months if tested while the infant is asleep; palmar grasp is present from birth to 6 months; plantar grasp is present from birth to 10 months.

Physical Development
		Length Range		Weight Range
		In	Cm	Lb	Kg
Birth	boys	18¼–21½	46.4–54.4	5½–9¼	2.54–4.15
	girls	17¾–20¾	45.4–52.9	5¼–8½	2.36–3.81
1 Month	boys	19¾–23	50.4–58.6	7–11¾	3.16–5.38
	girls	19¼–22½	49.2–56.9	6½–10¾	2.97–4.92
3 Months	boys	22¼–25¾	56.7–65.4	9¾–16¼	4.43–7.37
	girls	21¾–25	55.4–63.4	9¼–14¾	4.18–6.74
6 Months	boys	25–28½	63.4–72.3	13¾–20¾	6.20–9.46
	girls	24¼–27¾	61.8–70.2	12¾–19¼	5.79–8.73
9 Months	boys	26¾–30¼	68.0–77.1	16½–24	7.52–10.93
	girls	26–29½	66.1–75.0	15½–22½	7.0–10.17
12 Months	boys	28¼–32	71.7–81.2	18½–26½	8.43–11.99
	girls	27½–31¼	69.8–79.1	17¼–24¾	7.84–11.24
Psychomotor Development
Birth through 1st Month		Ability to suck, swallow, gag, cry, and maintain eye contact with a person. Head needs to be supported. Loud noises may cause a startle reflex.
2nd Month		May turn to either side when on their backs; will follow moving objects; able to lift head but not for a sustained period; begin to smile, frown, and turn away.
3rd Month		Greater movement and vocal response to stimuli; notice own hands and suck on them; head steady while supported.
4th and 5th Months		Able to lift head higher when lying on stomach; will reach for objects and may be able to encircle a bottle with both hands; may drool a lot; attempt to put all kinds of objects in mouth.
6th–9th Month		Develop ability to grasp and pick up food; are able to pull up to a sitting position and eventually will crawl; begin to make noises that sound like words and to recognize certain words; will play peek-a-boo.
9th–11th Month		Develop ability to handle food and to drink from a cup; may imitate sounds and say certain words; crawl by pulling body along with arms, and pull themselves to a standing position; they will point at objects and throw things; they want to feed themselves and to help with dressing and undressing; they will walk while holding a person's hand.
12th Month		Can eat food alone and drink from a cup with assistance; able to move around easily and crawl up stairs and out of crib.