Appearance and characteristics of the well term neonate
A term baby is one born between 37 and 42 weeks’ gestation. The dermis is well formed and the skin is usually smooth, with adequate subcutaneous fat and good muscle tone. The skin is generally well perfused although transient mild blueness of the feet and hands is normal at birth. The skin should be free from blemishes. Injuries such as cuts, bruises, marks from forceps blades or ventouse cups must be recorded. Movements, including chest wall movement, are symmetrical. Asymmetrical limb movement may indicate skeletal, muscle or nerve damage. The infant will be vigorous and the cry lusty, not weak or high-pitched.
The average weight at birth is 3.5 kg, with a normal range of 2.7–4.6 kg. The average length is 50 cm and the average occipitofrontal head circumference is 35 cm. The heart rate is between 110 and 160 beats/minute. The respiratory rate is 30–50 breaths/minute. Respiration is noiseless; respiratory ‘grunting’ must be investigated at once. The average systolic blood pressure is 75–100 mg/Hg, and the circulating blood volume is 85–90 mL/kg. The normal body temperature range is from 36.5 to 37.4°C (axillary).
Appropriate neurological development is indicated by the presence of primitive or primary reflexes. Some, such as the sucking reflex, are essential to survival. These reflexes can be elicited in the healthy term infant and should disappear with increasing maturity. Their absence in the neonate is suggestive of depression of the central nervous system. Similarly, persistence of primitive reflexes beyond infancy may be a sign of central nervous system pathology.
Reflexes that can be elicited in the neonatal period include (Figure 37.1):
- Sucking reflex
- Rooting reflex
- Moro (startle) reflex
- Palmar grasp reflex
- Plantar grasp reflex
- Stepping reflex
- Placing reflex
- Asymmetric tonic neck reflex.
Breastfeeding is the optimal method of infant nutrition and provides all the fluid and nutrient requirements for the infant. It also encourages proximity to the mother thus helping maintain body temperature and normal heart and respiratory rate. Some babies will not be breast fed, either from maternal choice or from necessity. For these babies safe, suitable breast milk substitutes are available. See Chapters 43 and 44 for further information on infant feeding.
The infant will usually pass urine and meconium within 24 hours of birth. Once milk feeding starts the stools change from dark green meconium to brownish (changing stools) then to yellow, usually at around 5 days of life. Urinary output is usually approximately 100–200 mL/kg/day by 7 days of life. However, as the renal cortex is relatively immature at birth the neonate has limited ability to concentrate urine and conserve water or electrolytes. A dehydrated infant will therefore still produce an adequate volume of urine. Urate crystals appear as a brick-red deposit in the nappy and are usually harmless.
Some variations in appearance of the newborn are considered normal (Figure 37.2). These include:
- Head shape: moulding and caput succedaneum should resolve quickly. Sutures and fontanelles are palpable. Cephalhaematomas are not usually evident at birth.
- Skin: white spots (milia) may appear on the face, naevi such as ‘stork bites’ and ‘port wine stains’ may be visible. Blue/grey patches (‘Mongolian’ spots) may be seen, commonly on the back or buttocks of Black, Asian or mixed heritage infants. The skin of a postdates infant may be dry and may crack. Blueness of the hands and feet should disappear within 48 hours. The appearance of jaundice within hours of birth is not normal. Vernix may be present in skin folds and a little lanugo may still be seen, although this has usually disappeared by 40 weeks.
- Mouth: teeth are occasionally present. The presence of tongue-tie may be seen.
- Limbs: positional talipes may be present.
- Genitalia: in female babies a white vaginal discharge may be seen and pseudomenstruation may occur. In male babies the testes should be descended.
- Trunk: transient breast enlargement may be seen in babies of either sex. There may be an umbilical hernia.