What is the normal range of physical examination indicators for infants over three months old

The normal range of physical examination indicators for infants over three months old includes a weight of 5-7 kilograms, a length of 58-65 centimeters, a head circumference of 38-42 centimeters, no murmurs on cardiopulmonary auscultation, symmetrical hip joint development, and neurological and behavioral standards such as follow-up and grasping. The specific values may vary among individuals due to factors such as genetics and feeding methods.

Weight gain is a core indicator for evaluating the nutritional status of infants. At the age of three months, male infants typically weigh 5.1-7.2 kilograms, while female infants weigh 4.7-6.7 kilograms. Infants who are adequately breastfed or formula fed gain 15-30 grams per day. Body length reflects the level of skeletal development, with male infants mostly in the range of 58.4-65.1 centimeters and female infants in the range of 57.3-63.8 centimeters. When measuring, it is necessary to maintain full extension of the lower limbs. Head circumference is related to brain volume, with a normal range of 38.5-42.3 centimeters for male infants and 37.7-41.5 centimeters for female infants. If the growth is too fast or too slow, it is necessary to check for hydrocephalus or microcephaly. Cardiopulmonary auscultation should show no abnormal sounds such as wheezing or wet rales, with a respiratory rate of 30-40 beats per minute and a heart rate of 120-160 beats per minute. Hip joint abduction should be above 80 degrees, and B-ultrasound screening can exclude developmental hip dislocation. In terms of neurobehavior, infants should be able to steadily raise their heads at 45 degrees, chase the red ball at 180 degrees, actively grasp the bell, and have startle or blink reactions to sounds. Parents should regularly record their growth curves and measure them in the morning when the baby is awake, avoiding immediate testing after eating. If the weight does not increase for two consecutive weeks, the head circumference increases by more than 3 centimeters per month, or there is abnormal muscle tone, the patient should be promptly referred to the pediatrics or pediatric health department. Pay attention to feeding according to daily needs, ensure 14-17 hours of sleep per day, and perform prone head up training to avoid excessive wrapping that affects hip joint development.