An infant or baby is the very young offspring of human beings. Infant (from the Latin word infans, meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term baby. The terms may also be used to refer to juveniles of other organisms. A newborn is, in colloquial use, an infant who is only hours, days, or up to one month old. In medical contexts, a newborn or neonate (from Latin, neonatus, newborn) is an infant in the first 28 days after birth; the term applies to premature, full term, and postmature infants.
Before birth, the offspring is called a fetus. The term infant is typically applied to very young children under one year of age; however, definitions may vary and may include children up to two years of age. When a human child learns to walk, they are called a toddler instead.
During labour and birth, the infant's skull changes shape to fit through the birth canal, sometimes causing the child to be born with a misshapen or elongated head. It will usually return to normal on its own within a few days or weeks. Special exercises sometimes advised by physicians may assist the process.
Some newborns have a fine, downy body hair called lanugo. It may be particularly noticeable on the back, shoulders, forehead, ears and face of premature infants. Lanugo disappears within a few weeks. Infants may be born with full heads of hair; others, particularly caucasian infants, may have very fine hair or may even be bald. Amongst fair-skinned parents, this fine hair may be blonde, even if the parents are not. An infant's hair color and texture can change: red can give way to blond, curly can go straight, and thick, dark hair could reappear a lot sparser and lighter. The scalp may also be temporarily bruised or swollen, especially in hairless newborns, and the area around the eyes may be puffy.
A newborn's genitals are enlarged and reddened, with male infants having an unusually large scrotum. The breasts may also be enlarged, even in male infants. This is caused by naturally occurring maternal hormones and is a temporary condition. Females (and even males) may actually discharge milk from their nipples (sometimes called witch's milk), or a bloody or milky-like substance from the vagina. In either case, this is considered normal and will disappear with time.
Infants cry as a form of basic instinctive communication. A crying infant may be trying to express a variety of feelings including hunger, discomfort, overstimulation, boredom, wanting something, or loneliness.
Breastfeeding is the recommended method of feeding by all major infant health organizations. If breastfeeding is not possible or desired, bottle feeding is done with expressed breast-milk or with infant formula. Infants are born with a sucking reflex allowing them to extract the milk from the nipples of the breasts or the nipple of the baby bottle, as well as an instinctive behavior known as rooting with which they seek out the nipple. Sometimes a wet nurse is hired to feed the infant, although this is rare, especially in developed countries.
Adequate food consumption at an early age is vital for an infant's development. The foundations of optimum health, growth, and neurodevelopment across the lifespan are established in the first 1000 days of life. From birth to six months, infants should consume only breast milk or an unmodified milk substitute. As an infant's diet matures, finger foods may be introduced as well as fruit, vegetables and small amounts of meat.
Experiments have been done with infants up to four months of age using both positive touch (stroking or cuddling) and negative touch (poking, pinching, or tickling). The infants who received the positive touch cried less often and vocalized and smiled more than the infants who were touched negatively. Infants who were the recipients of negative touch have also been linked with emotional and behavioral problems later in life. A lower amount of physical violence in adults has been discovered in cultures with greater levels of positive physical touching.
Caregivers of an infant are advised to pick up on the infant's facial expressions and mirror them. Reproducing and empathizing with their facial expressions enables infants to experience effectiveness and to recognize their own actions more easily (see mirror neurons). Exaggeratedly reproduced facial expressions and gestures are recommended, as they are clearer forms of expression. The baby's babbling should also be picked up and repeated. By imitating each other's sounds the first simple dialogues are initiated. Accentuated pronunciation and melodic intonation make it easier to recognize individual words in a sentence. However, it is not advisable to use simplified "baby talk" (e.g. "Did you 'ouch'?" instead of, "Did you hurt yourself?").
Even if parents cannot yet understand infants' babbling, a timely response by parents to babbling leads to faster language acquisition. This was confirmed by researchers who first studied mothers' behavior towards 8-month-old infants and later tested the infants' vocabulary when they were 15 months old. A first important development of infants is the discovery that they can influence their parents through babbling (development of intentional communication). Parents can encourage this by engaging with their infants in babbling. This in turn promotes further language development, as infants then turn to their parents more often.
Previous studies have shown that the infant's speech is encouraged when parents, for example, smile in the infant's direction or touch the infant every time the infant looks at them and babbles. It also helps if parents respond to what they think their baby is saying (for example, giving a ball or commenting when the baby looks at the ball and babbles). Responding to sounds produced when the baby looks at an object (object-directed vocalizations) thus provide an opportunity to learn the name of the object. In this way, babies also learn that sounds are associated with objects. However, language development is only achieved if parents react positively (e.g. smile) in response to the infant's babbling. A high response rate without a connection to the infant's utterances does not lead to language promotion. It is detrimental to language development if a mother instead tries to divert the infant's attention to something else.
In 2020, a Finnish study established (according to the research leader) for the first time a reference value for infant sleep quality based on a large data set (about 5,700 babies). Almost 40% of the participating parents with eight-month-old babies said they were worried about their sleep. In fact, sleep problems were common; however, children fall asleep faster, wake up less often during the night and stay awake less late at night the older they get. At the same time, total sleep time decreases.
Wearing has a calming effect on infants. A 2013 study showed that infants placed in a cradle cried and kicked more often and had an increased heart rate (so the infants were stressed), while those picked up and carried by the mother while walking around calmed down significantly. The effect of being held motionless in the arm was intermediate between that of being carried around and that of being put down. That carrying (e.g., in a baby sling) makes infants more content and makes them cry less had already been shown in a randomized study in 1986.
Attachment theory is primarily an evolutionary and ethological theory whereby the infant or child seeks proximity to a specified attachment figure in situations of alarm or distress for the purpose of survival. The forming of attachments is considered to be the foundation of the infant/child's capacity to form and conduct relationships throughout life. Attachment is not the same as love or affection although they often go together. Attachment and attachment behaviors tend to develop between the age of 6 months and 3 years. Infants become attached to adults who are sensitive and responsive in social interactions with the infant, and who remain as consistent caregivers for some time. Parental responses lead to the development of patterns of attachment, which in turn lead to 'internal working models' which will guide the individual's feelings, thoughts, and expectations in later relationships. There are a number of attachment 'styles' namely 'secure', 'anxious-ambivalent', 'anxious-avoidant', (all 'organized') and 'disorganized', some of which are more problematic than others. A lack of attachment or a seriously disrupted capacity for attachment could potentially amount to serious disorders.
Infants respond to the sound of snake hissing, angry voices of adults, the crackling sound of a fire, thunder, and the cries of other infants. They have a drop in heart rate, their eyes blinking, increased turning toward the speakers or parent, all of these indicating that they were paying more attention. This is believed to be an evolutionary response to danger. Babies' ability to accurately locate sounds is refined during their first year.
The infant is undergoing many adaptations to extrauterine life, and its physiological systems, such as the immune system, are far from fully developed. Potential diseases of concern during the neonatal period include:
Infant mortality is the death of an infant in the first year of life, often expressed as the number of deaths per 1000 live births (infant mortality rate). Major causes of infant mortality include dehydration, infection, congenital malformation and SIDS.
This epidemiological indicator is recognized as a very important measure of the level of health care in a country because it is directly linked with the health status of infants, children, and pregnant women as well as access to medical care, socioeconomic conditions, and public health practices. 781b155fdc