Often more overlooked than history in evaluating neonates is information about the placenta and the clues it provides about the gestational history. Several features of the placenta and cord can be readily assessed on gross examination by anyone at the time of delivery. The placenta should be examined for size, odor, color, and the number and character of fetal membranes. In the last trimester the ratio of fresh placental weight to infant weight is normally 1:6. There should be a uniform thickness and density throughout. Depressions and adherent clots or changes in firmness on the maternal surface suggest abruption or infarction. The placenta is essentially odorless except for a slight odor of fresh blood. Malodor may indicate the presence of infection although this is controversial.

The color of the fetal surface changes with gestational age (GA), but pallor or plethora suggest aberrations in fetal blood volume or hemoglobin level. Elevated bilirubin in the amniotic fluid stains the placenta bright yellow. Meconium will discolor the fetal surface greenish-brown but so too can old blood. If either meconium passage or bleeding occurred more than 1 day prior to delivery, it can be difficult to differentiate the two by gross examination.

The fetal surface should be examined for cloudiness of fetal membranes, which suggests an inflammatory reaction but not necessarily due to infection. Nodules on the amnion indicate prolonged, extreme oligohydramnios. Fetal pulmonary hypoplasia is highly probable in this setting and is a key finding in renal agenesis. Their presence suggests futility if resuscitation is underway.

In multiple gestations with a single placenta, the dividing membranes should be assessed. Membranes can be teased apart and counted: four layers indicate dichorionic placentation and two layers indicate a monochorionic placenta. With a dichorionic placenta or completely separate placentas and same gender twins, one cannot say if they are identical or fraternal from the placental examination. Monochorionicity has traditionally been viewed as patho-gnomonic for identical twins; however, a recent report refutes this assertion (8). Just as monozygotic twins can have separate placentas, dizygotic twins can have tightly fused placentas that appear to be one mass. If there are any remnants of vessels seen in translucent dividing membranes held to a light, there are four membrane layers. If there is only a transparent membrane with no chorionic remnants, it is likely to contain only amnion.

Estimation of GA by physical examination is possible because there is a predictable pattern of physical changes that occur throughout gestation. The most popular score for GA assessment was originally developed in part by Saint-Anne-Dargassies (9), Amiel-Tison (10), and Dubowitz and associates (11). These systems have been applied to infants with GAs of 22 to 27 weeks despite the fact that no infants below 28 weeks were included in their development. In these very premature infants, the GA was consistently overestimated by up to 2 weeks when compared to reliable ultrasound dates. Conversely, in postterm pregnancies they tended to underestimate the age of postterm infants (12). A further modification by Ballard and associates (13), which included infants with GAs ≥26 weeks, purportedly improved reliability. However, even in infant cohorts of <1,500 g and <2,500 g, the Ballard score similarly yielded a 1- to 2-week error, being greatest at lower birth weights (14,15,16,17). A final modification produced the New Ballard Score (NBS), which claimed to improve the accuracy of age assessment to within 1 week (Fig. 19-1) (18). The strength of this study was inclusion of infants ≥20 weeks, designed to improve accuracy because of larger numbers of extremely premature infants. However a recent study in 24- to 27-week premature infants refuted these findings, showing persistent miscalculation by up to 2 weeks (19). Some have attributed the tendency to overestimate true GA to accelerated neurologic maturity (14,18). It is likely that factors contributing to preterm birth cause stress in the developing fetus and bring about faster neurologic maturation compared to unstressed fetuses in continuing pregnancies. Using last menstrual period (LMP) or early ultrasound as the gold standard, some studies show a closer correlation between physical criteria alone and GA compared to neurologic or total Ballard score. In a multicenter study, infants who were small for their GA had consistent overestimation of their GA. (14).

Due to the inaccuracy of the NBS in extreme prematurity, one must continue to use maternal LMP and early ultrasound as the gold standard for determining GA (see Chapter 12). This becomes imperative when deciding aggressiveness of support in an infant born at 22 to 23 weeks by dates. Despite the aforementioned concerns, the NBS remains the best method available to estimate GA in the presence of uncertain dates.

Other methods for GA assessment have emerged over the years. Prior to gestation of 27 weeks, the cornea is too hazy to permit examination of intraocular structures. The vessels in the anterior vascular capsule of the lens mature in a predictable enough pattern in the last trimester to allow determination of GA with a 2-week margin of error in infants at 28 to 34 weeks of gestation. (20) The exam must be performed within the first 24 to 48 hours of life as the vessels atrophy rapidly after this time. It may prove useful when a neurologic abnormality and uncertain dates render the NBS inadequate. As well, it has been validated in infants who are small for GA, which compromises the accuracy of the NBS (21).

One final technique is the use of changes in skin reflectance during fetal development to determine GA of infants at 24 to 42 weeks of gestation (22). A reflectance spectrophotometer at a wavelength of 837 nm obtains a measurement of skin reflectance independent of melanin, yielding an estimate of GA unaltered by skin color. Initially considered for use in black infants who were thought to be more neurologically mature at birth than other ethnic groups, the requirement for special equipment and discovery that GA assessment tools were not influenced by racial differences likely prevented widespread use of this technique (23).

Accurate estimation of GA requires experience and consideration of the infant’s history and overall condition at the time of scoring; for example, maternal medications or drugs and the infant’s fetal position or sleep state affect the neuromuscular response in a normal infant. Significant hypertonia or hypotonia is particularly powerful in affecting the neuromotor scores but does not affect the physical maturity score. Examination as soon as possible after initial stabilization or by 12 hours increases the accuracy in gestations shorter than 28 weeks (18). The use of NBS is particularly
attractive for neonates who are immature and instrumented because it does not require lifting the infant. Although described here separately from other components of the examination, the steps for assessing GA can be done as part of the general physical examination and can provide information for the neurologic evaluation. The neurologic examination of infants during the first year continues to use a number of these assessment elements (24,25).

The resting posture is that observed with the infant in a quiet unrestrained environment. Tone increases in a caudocephalad direction to a pattern of full flexion at term (Fig. 19-1).

The square window is assessed by flexing the wrist and measuring the minimal angle between the palm and flexor surface of the forearm. This angle decreases with advancing
GA. Conditions of marked intrauterine compression, such as severe oligohydramnios, increase wrist flexion. As an extremely premature newborn advances through corrected GA, he or she will not continue to develop as much wrist flexion after birth as the infant would have had he or she stayed in utero.

The scarf sign indicative of shoulder and superior axial tone is assessed by pulling the hand across the chest to encircle the neck as a scarf and observing the position of the elbow in relation to the midline. There is decreased range and a higher score if there is marked obesity, chest wall edema, an abnormally shortened humerus, or shoulder girdle hypertonicity. Brachial plexus injury or generalized hypotonia produces a spuriously low score.

With the infant supine and head midline, arm recoil is assessed by first flexing the elbow and holding the arm against the forearm for 2 to 5 seconds. The elbow is then fully extended and released with observation of how quickly and fully the infant resumes a flexed posture. Assessing recoil should not be done as part of testing arm traction or with forceful extension because other responses may interfere with a normal reaction. Any pathology affecting the motor strength or tone of the arm will decrease this score.

To determine the popliteal angle, one should first flex the hips with the thighs alongside the abdomen rather than over the front. With the hips held in flexion and the pelvis flat, the knee is then extended as far as possible to estimate the popliteal angle. If an infant was in frank breech presentation with legs extended, the popliteal angles would be greater than expected for age.

In the heel-to-ear maneuver, the legs are held together and pressed as far as possible toward the ears without lifting the pelvis from the table. The angle made by an arc from the back of the heel to the table decreases with maturity.

Skin in the most premature infants is gelatinous and almost transparent, allowing the abdominal vessels to be visible. It becomes opaque with maturity as it thickens and keratinizes, eventually shedding the lubricating vernix after it dries and cracks.

Lanugo, which is the fine hair evenly distributed over the body, first emerges at 19 to 20 weeks, but for a few weeks after initial emergence it is not readily apparent. Maximally apparent at 27 to 28 weeks, lanugo sheds first from the areas of greatest contact. Lanugo is distinct from the more pigmented body hair that may be quite prominent in infants of medium to dark complexion.

Assessment of the plantar surface includes measuring the foot because its length reliably corresponds to early GA. With normal muscle activity and uterine compression, creases develop in the sole, progressing from the toes toward the heel. Inappropriate sole creasing is seen in infants with serious neuromotor deficit in the lower extremities (e.g., decreased creasing or only deep vertical creasing) or with oligohydramnios (e.g., increased creasing).

The breast develops with an increase in color, stippling of the areola, and increase in the size of the breast tissue. Although the volume of the breast somewhat depends on fetal nutrition and fat deposition, areolar development with increasing GA is more consistent and independent of these factors.

Ear cartilage becomes firmer with gestation if there is no continuous, extrinsic pressure and the auricular muscles have normal anatomy and activity. Concurrently, as gestation advances, the number of ear folds increase as well. Unfusing of the eyelids can occur over several weeks, and a fused condition by itself is not a sign of extreme, nonviable immaturity. Opening starts by 22 weeks; complete unfusing is evident by at latest 28 weeks (18).

Maturity of the external genitalia is one of the more reliable individual indicators of GA (18). Due to timed descent in the third trimester, testicular progress through the canal into the scrotum is a GA marker. The testes are usually palpable high in the scrotum at 36 weeks and fully descended by 40 weeks. For the scrotum to develop fully into a pendulous, rugose, term appearance, testicular descent must occur at some time, even if the sac is empty at the time of birth.

The appearance of term female genitalia depends on fat deposition and is abnormally immature in a poorly nourished infant. The clitoris approaches term size well before 38 weeks so it is disproportionately large in premature females (26,27). The appearance of a pigmented vertical line, the linea nigra, above the pubis toward the umbilicus suggests a GA of at least 36 weeks.

If there is a discrepancy between expected and achieved scores, factors that influence the demonstrated findings should be sought before assigning GA.

Resting posture reflects progressive flexion into the position assumed when a term fetus occupies virtually all available intrauterine space and is no longer in a freely floating state. To minimize the volume occupied, this flexion logically progresses in a caudal to cephalic sequence. Compression from oligohydramnios accelerates flexion; it gives an artificially advanced estimate of maturity. Conversely, poor fetal motor activity over a long period spuriously decreases estimated age. Fetuses with markedly decreased motor activity and polyhydramnios have decreased plantar and palmar horizontal creasing and inappropriately immature posturing. Any condition affecting the position or activity of the lower extremities, such as frank breech presentation with hyperextended knees or myelomeningocele with paresis leads to an aberrantly lowered neuromotor score. Similarly, an infant who is hypotonic from illness or sedation has less flexion than normal for true GA.

Infants weighing less than 2,500 g are low birth weight (LBW) regardless of GA; very low birth weight (VLBW)
refers to a weight less than 1,500 g, and extremely low birth weight (ELBW) indicates an infant weighing less than 1,000 g. Classification by these weight groups helps establish the level of risk for neonatal and long-term morbidity and mortality, particularly when the weight classification is coupled with an accurate GA (28).

Of all measurements, crown-heel length is the most subject to variability, because it depends on achieving full extension of an infant who is more naturally in flexion. This measurement is performed with the infant supine, neck neutral, leg fully extended, and ankle flexed to 90 degrees. If there is deviation from an expected norm, the first step in evaluation is to remeasure the infant for confirmation. Although not part of routine practice, a measuring board definitely improves accuracy.

When anomalies of the lower extremities make crown-heel length implausible, the crown-rump measurement may still be feasible. Crown-rump length is measured with the infant supine and the hips flexed 90 degrees. Congenital dwarfism may be classified as those with a short trunk, short legs, or both. These subtypes can be readily differentiated by the crown-rump to total length ratio. From 27 to 41 weeks of gestation the value is fairly consistent at 0.665 ± 0.027 (29). The ratio is normal if a condition causes proportional reductions in length of the upper and lower body; increased if the legs are shortened to a greater degree; and decreased if the trunk is foreshortened. Standards for separate lengths of upper and lower limbs are available (30,31).

The head circumference is the largest dimension around the head obtained with a tape placed snugly above the ears. This is the occipital frontal circumference (OFC). Head circumference undergoes a marked increase during the last trimester, averaging 25 cm at 28 weeks and 35 cm at term (32). The average head circumference is 0.5 cm greater in male compared with female neonates (33). Due to greater reliability of repeated measurements, paper rather than reusable cloth tape measures should be used (34). Minor changes in head circumference occur during the first week after birth as scalp edema and molding resolve. The molding seen after prolonged breech positioning can lead to an OFC that is as much as 2 cm higher than it will be after molding resolves.

The OFC predictably falls on the same percentile curve as the length. If the OFC differs from length by more than one quartile, the cause should be sought because head size in part reflects brain growth. The most frequent reason for a head percentile to exceed that of length is familial. In this situation the head circumference follows a persistently higher but consistent growth curve. In contrast, pathologic macrocephaly tends to cross to higher percentile curves as it progresses. A decreased rate of head growth, manifested by a flat curve or by dropping to a lower percentile, may indicate poor brain growth, atrophy, or premature suture fusion (craniosynostosis [CS]). As OFC may be normal in some forms of CS, the head width index (maximal biparietal diameter divided by the OFC) and head length index (glabella to occipital prominence divided by the OFC) may be more informative (35). For example, a patient with scaphocephaly secondary to sagittal suture closure may have a normal OFC but have an abnormally small width index and excessive length index. Normal ranges for these indices are available (35). The fetal head circumference exceeds the abdominal circumference until 32 weeks. Between 32 and 36 weeks, the two circumferences are equivalent, and after 36 weeks the abdominal circumference normally is greater.

Interpretation of growth parameters requires plotting the measurements on percentile charts constructed from a similar race and environmental population. If birth weight falls between the 10th and 90th percentiles for a given GA, the infant is appropriate for gestational age (AGA); if less than the 10th percentile, the infant is small for gestational age (SGA); and if above the 90th percentile, the infant is large for gestational age (LGA). Some literature cites the 3rd and 97th percentiles as outer limits, but for most clinical purposes this broader range underselects for some at-risk infants, particularly in the lower sizes. Accuracy in GA assessment is critical in determining if a weight is appropriate. AGA infants born at term are at lowest risk for problems associated with neonatal mortality and morbidity (28).

Infants are considered symmetric if the three parameters of weight, length, and head circumference fall on the same curve. The infant is asymmetric if the parameters are on different curves, usually with the weight on a curve lower than those of the head circumference or length. If an infant has either a slowing of intrauterine growth rate documented by serial fetal sonography or a presumed slowing by very low weight for length measurements, he or she is classified as having intrauterine growth retardation (IUGR). All infants who fall below the 10th percentile for weight are both SGA and IUGR. Infants above the 10th percentile are AGA but may be IUGR if they did not achieve their expected growth potential. An infant who demonstrates a deceleration in growth from the 50th to the 20th percentile during the last trimester due to maternal hypertension is such an example.

Infants who are SGA, IUGR, or LGA are at risk for perinatal and long-term problems. Several of the problems encountered by LGA infants include the following:

A routine neonatal examination, normally 5 to 10 minutes, should take place in a quiet, warm environment. The room’s light should be bright enough to detect skin markings and color but not so bright as to discourage open eyes. When an infant is ill, attention to optimizing the environment and recognizing the potential effect of noxious nursery surroundings on his or her state is fundamental.

Even healthy infants do not tolerate handling in extended examinations. The sicker or more immature they are, the less they tolerate manipulation and environmental assaults. For all examinations, the prime consideration must be that no harm should come by the process. In routine care situations, having one or both parents present during an examination allows discussion about physical findings and offers the opportunity to point out behaviors that can help them better understand their infant. They can address directly any questions about history or therapy at that time as well.

The specifics of neonatal examination are discussed in the following sections. Some systems that are discussed in more detail in other chapters are given less emphasis in this chapter than they would merit in an actual examination.

Inspection begins before making any physical contact and from enough of a distance to encompass the infant as a whole. An immediate assessment of wellness can come from simply noting the state, color, respiratory effort, posture, and spontaneous activity. Even simple observations of spontaneous movement patterns can suggest future neurologic deficits or well-being (36).

Important indicators of infant well-being are the states or levels of arousal the infant achieves throughout the examination and throughout the day as described by the parents or nursing staff. One categorization of states listed here was originally defined by Prechtl and Beintema (37). Modifications have been made but are not clinically important for general assessments (38,39,40,41).

During examination, a healthy infant should demonstrate several levels of arousal. The most useful states for assessing an infant are those of light sleep and quiet awake so irritating maneuvers are held until the conclusion of the assessment. What it takes to assist an infant in moving from one state to another or how well he or she does it without assistance is noteworthy. Because the deep sleep that follows a recent feeding may give an appearance of lethargy on arousal, knowing the feeding history and pattern is prerequisite to determining aptness of state.

Newborns spend nearly two-thirds of each day in sleep (42). Each 24-hour period involves cycling between periods of active sleep (AS) and quiet sleep (QS). These periods are also known as rapid eye movement (REM) and non-REM sleep, respectively. During AS, infants demonstrate phasic limb movements, eye movements, and irregular respirations. Breathing is typically rapid and shallow interspersed between periods of more regular respiration (43). In comparison, QS is characterized by regular respirations and the absence of eye and limb movements. As GA increases, the proportion of time spent in QS increases (44). Stress during the perinatal period may alter the proportion of time spent between AS and QS as firstborns and infants born after cesarean section spend more time in AS than babies from subsequent pregnancies or vaginal deliveries (42).

Quieting an infant may require anything from simply stopping the handling to holding and talking to him or her. The amount of time spent in unstimulated crying is normally limited in the first 24 hours but may increase significantly each day thereafter. Excessive crying that requires more than routine consoling, particularly if there are no intervals of quiet alert states, indicates abnormal irritability, but other causes include a proper response to pain or to a cold environment (45,46).

Assessment of facies includes looking for symmetry, size, shape, and the relations of all parts of the face and how the infant holds or uses them. A seemingly unusual facial appearance dictates analyzing the individual components to decide if the constellation represents malformation, deformation, a syndrome, or merely familial appearance.