& Wolke, 2015). It is administered in the first few days after birth to assess the newborn’s neurological competence as indicated by the responsiveness to the physical and social environment, perception, and motor skills such as activity level and the ability to bring a hand to the mouth (Nugent, 2013). The NBAS also assesses infants’ attention and state changes, including excitability and ability to settle down after being upset. When parents observe and participate in their baby’s NBAS screening, they learn about their newborn’s perceptual and behavioral capacities and are better able to elicit gazes, quiet fussiness, and tend to be more responsive to their infants (Benzies et al., 2013).
Table 3.1
Source: Apgar (1953).
The Newborn’s Perceptual Capacities
Until recent decades, it was widely believed that the newborn was perceptually immature—blind and deaf at birth. Developmental researchers now know that the newborn is more perceptually competent than ever imagined. For example, both taste and smell are well developed at birth. Taste appears to function well before birth because research has shown that fetuses swallow sweetened amniotic fluid more quickly than bitter fluid (Ventura & Worobey, 2013). Newborns can discriminate smells and calm in response to the scent of amniotic fluid and other familiar smells (Neshat et al., 2016; Rotstein et al., 2015). The visual capacities of the newborn are more limited and focused primarily on the near environment. Newborn vision is blurry and best at about 18 inches away—the typical distance to a parent’s face when holding the infant.
The most remarkable newborn capacities for perception and learning are auditory in nature. Pregnant women often report that they notice fetal movements in response to a loud sound like a car horn or a door slamming. The fetus responds to auditory stimulation as early as 23 to 25 weeks after conception (Hepper, 2015). By 32 to 34 weeks, the fetus responds to the mother’s voice as indicated by a change in heart rate (Kisilevsky & Hains, 2011). Prior to birth, the fetus can discriminate voices and speech sounds (Granier-Deferre, Ribeiro, Jacquet, & Bassereau, 2011). At birth, newborns show preferences for speech sounds, their mother’s voice, their native language, and even stories and music heard prenatally (Moon, Cooper, & Fifer, 1993). Moreover, from birth, the newborn is an active listener, paying attention to sounds and naturally taking advantage of opportunities to learn (Vouloumanos, Hauser, Werker, & Martin, 2010).
Newborn States of Arousal
Newborns display regular cycles of eating, elimination, and states of arousal or degrees of wakefulness. In a typical day, newborns move in and out of five infant states or levels of arousal, as shown in Table 3.2. Most newborns spend about 70% of their time sleeping and wake every 2 to 3 hours. These short stretches of sleep alternate with shorter periods of wakefulness that are primarily devoted to feeding. During the first month, infants often move rapidly from one state to another, dozing off during feeding, for example. Naps are punctuated by periods of drowsiness, alert and unalert activity, and crying.
Table 3.2
Sources: Prechtl (1974) and Wolff (1966).
Newborn sleep cycles are brief, lasting from 45 minutes to 2 to 3 hours, but similar to those of adults in that they consist of both REM sleep, or rapid eye movement sleep, and non-REM sleep (Korotchikova, Stevenson, Livingstone, Ryan, & Boylan, 2016). When a person is in REM sleep, the brain wave activity is remarkably similar to that of the waking state. The eyes move back and forth beneath closed lids; heart rate, blood pressure, and breathing are uneven; and there are slight body movements. It is sleep. Newborns spend about half of their sleep time in REM, but by ages 3 to 5, children spend about 15% to 20% of their sleep in REM, similar to adults (Grigg-Damberger & Wolfe, 2017; Kobayashi, Good, Mamiya, Skinner, & Garcia-Rill, 2004).
Why do newborns spend so much time in REM sleep? REM sleep is associated with dreaming in both children and adults. Neonates spend about 18 hours sleeping each day and therefore spend little time in the active alert state in which they get stimulation from the environment. REM is a way that the brain stimulates itself, which is important for the growth of the central nervous system (Grigg-Damberger & Wolfe, 2017). This view of REM sleep as serving a self-stimulation function is supported by findings that fetuses and preterm babies, who are even less able to take advantage of external stimulation than are newborns, spend even more time in REM sleep. In addition, neonates with low REM sleep activity tend to score lower on mental tests at 6 months of age (Arditi-Babchuk, Feldman, & Eidelman, 2009).
Low-Birthweight Infants: Preterm and Small-for-Date Babies
Low-birthweight infants require extensive care. They are at risk for poor developmental outcomes and even death.
Andrew Lichtenstein/Corbis News/Getty Images
About 8% of infants born in the United States each year are low birthweight (J. A. Martin et al., 2018). Low-birthweight infants may be preterm, or premature (born before their due date), or small for date, who are full term but have experienced slow growth and are smaller than expected for their gestational age. Infants are classified as low birthweight when they weigh less than 2,500 grams (5.5 pounds) at birth; very low birthweight refers to a weight less than 1,500 grams (3.5 pounds), and extremely low birthweight refers to a weight less than 750 grams (1 pound, 10 ounces). Infants who are born with low birthweight are at risk for a variety of developmental difficulties. Indeed, their very survival is far from certain; the Centers for Disease Control and Prevention lists prematurity and low birthweight among the leading causes of infant mortality, accounting for 35% of mortality cases in infancy (Mathews & MacDorman, 2013). Infants most at risk for developmental challenges, disabilities, and difficulty surviving are those with extremely low birthweight
Contextual Risks for Low Birthweight
The prevalence of low birthweight varies with ethnicity and socioeconomic status, as shown in Figure 3.10. In 2016, non-Hispanic Black infants were more than twice as likely to be born low birthweight (11%) as non-Hispanic White and Hispanic infants (5% and 6%, respectively) (Womack, Rossen, & Martin, 2018). Contextual influences, such as neighborhood and socioeconomic factors, interact in complex ways to influence low birthweight. For example, neighborhood disadvantage and the stressors that accompany it are associated with an increased risk for low birthweight (Ncube, Enquobahrie, Albert, Herrick, & Burke, 2016). In one study, low birthweight rates were higher in non-Hispanic Black mothers than non-Hispanic White mothers, but the racial difference declined (but did not disappear) when the researchers took into account financial and relationship stresses (Almeida, Bécares, Erbetta, Bettegowda, & Ahluwalia, 2018). These findings suggest that contextual factors, such as differences in experienced stress, may influence some of the racial differences in low birthweight.
Figure 3.10 Very Low and Low Birthweight Rates, by Maternal Race/Ethnicity, 2015
Source: Centers for Disease Control and Prevention (2018c).
Socioeconomic disadvantage interacts with race and ethnicity in complex ways to influence low birthweight. For example, in one study of over 10,000 Californian women, the most economically disadvantaged Black and White women showed similar low-birthweight rates, regardless of race (Braveman et al., 2015). Rates of low birthweight declined with a rise in income for all women, but the racial disparity in low birthweight grew such that greater socioeconomic advantage was more strongly associated