NCM 107 Care of Mother, Child and Adolescent (Well Clients) pt. 1

A.     VITAL STATISTICS

Vital statistics measured in a newborn are weight, length, and head and chest circumference. Be sure all health care providers involved with newborns are aware of safety issues specific to newborn care when taking these measurements such as not leaving a newborn unattended on a bed or scale.

ü  Weight The birth weight of newborns varies depending on the racial, nutritional, intrauterine, and genetic factors that were present during conception and pregnancy. The weight in relation to the gestational age should be plotted on a standard neonatal graph. Plotting weight this way helps identify newborns who are at risk because of their small size. This information also separates those who are small for their gestational age (newborns who have suffered intrauterine growth restriction) from preterm infants (infants who are healthy but small only because they were born early). These first measurements also establish a baseline for future evaluation. Plotting weight in conjunction with height and head circumference is also helpful because it highlights disproportionate measurements. All three of these measurements should fall near the same percentile in an individual child. For example, a newborn who falls within the 50th percentile for height and weight but whose head circumference is in the 90th percentile may have abnormal head growth. A newborn who is in the 50th percentile for weight and head circumference but in the 3rd percentile for height may have a growth problem The average birth weight (50th percentile) for a white, mature female newborn in the United States is 3.4 kg (7.5 lb); for a white, mature male newborn, it is 3.5 kg (7.7 lb). Newborns of other races weigh approximately 0.5 lb less. The arbitrary lower limit of normal for all races is 2.5 kg (5.5 lb). Birth weight exceeding 4.7 kg (10 lb) is unusual, but weights as high as 7.7 kg (17 lb) have been documented. If a newborn weighs more than 4.7 kg, the baby is said to be macrosomic and a maternal illness, such as diabetes mellitus, must be suspected (Kwik et al., 2007). Second-born children usually weigh more than first-born. Birth weight continues to increase with each succeeding child in a family. During the first few days after birth, a newborn loses 5% to 10% of birth weight (6 to 10 oz). This weight loss occurs because a newborn is no longer under the influence of salt and fluid-retaining maternal hormones. Diuresis begins to remove a part of the infant’s high fluid load. A newborn also voids and passes stool. Because approximately 75% to 90% of a newborn’s weight is fluid, all three of these measures reduce weight. In addition, breastfed newborns have a limited intake until about the third day of life because of the relatively low caloric content and amount of colostrum they ingest. If newborns are formula-fed, their intake during this time is also limited because of the time needed to establish effective sucking. After this initial loss of weight, a newborn has 1 day of stable weight, then begins to gain weight. The breastfed newborn recaptures birth weight within 10 days; a formula-fed infant accomplishes this gain within 7 days. After this, a newborn begins to gain about 2 lb per month (6 to 8 oz per week) for the first 6 months of life.

ü  Length The average birth length (50th percentile) of a mature female neonate is 53 cm (20.9 in). For mature males, the average birth length is 54 cm (21.3 in). The lower limit of normal length is arbitrarily set at 46 cm (18 in). Although rare, babies with lengths as great as 57.5 cm (24 in) have been reported.

ü  Head Circumference In a mature newborn, the head circumference is usually 34 to 35 cm (13.5 to 14 in). A mature newborn with a head circumference greater than 37 cm (14.8 in) or less than 33 cm (13.2 in) should be carefully assessed for neurologic involvement, although occasionally a well newborn falls within these limits. Head circumference is measured with a tape measure drawn across the center of the forehead and around the most prominent portion of the posterior head.

ü  Chest Circumference The chest circumference in a term newborn is about 2 cm (0.75 to 1 in) less than the head circumference. This is measured at the level of the nipples. If a large amount of breast tissue or edema of breasts is present, this measurement will not be accurate until the edema has subsided.