Infant Behavior: Any observable response or action of a neonate or infant up through the age of 23 months.Temperament: Predisposition to react to one's environment in a certain way; usually refers to mood changes.Crying: To utter an inarticulate, characteristic sound in order to communicate or express a feeling, or desire for attention.Sucking Behavior: Any suction exerted by the mouth; response of the mammalian infant to draw milk from the breast. Includes sucking on inanimate objects. Not to be used for thumb sucking, which is indexed under fingersucking.Mother-Child Relations: Interaction between a mother and child.Infant Care: Care of infants in the home or institution.Maternal Behavior: The behavior patterns associated with or characteristic of a mother.Object Attachment: Emotional attachment to someone or something in the environment.Infant, Premature: A human infant born before 37 weeks of GESTATION.Infant, Newborn: An infant during the first month after birth.Child Development: The continuous sequential physiological and psychological maturing of an individual from birth up to but not including ADOLESCENCE.Child Behavior: Any observable response or action of a child from 24 months through 12 years of age. For neonates or children younger than 24 months, INFANT BEHAVIOR is available.Mothers: Female parents, human or animal.Behavior, Animal: The observable response an animal makes to any situation.Infant, Premature, DiseasesInfant Food: Food processed and manufactured for the nutritional health of children in their first year of life.Feeding Behavior: Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.Infant Formula: Liquid formulations for the nutrition of infants that can substitute for BREAST MILK.Infant Mortality: Postnatal deaths from BIRTH to 365 days after birth in a given population. Postneonatal mortality represents deaths between 28 days and 365 days after birth (as defined by National Center for Health Statistics). Neonatal mortality represents deaths from birth to 27 days after birth.Social Behavior: Any behavior caused by or affecting another individual, usually of the same species.Sudden Infant Death: The abrupt and unexplained death of an apparently healthy infant under one year of age, remaining unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history. (Pediatr Pathol 1991 Sep-Oct;11(5):677-84)Infant, Newborn, Diseases: Diseases of newborn infants present at birth (congenital) or developing within the first month of birth. It does not include hereditary diseases not manifesting at birth or within the first 30 days of life nor does it include inborn errors of metabolism. Both HEREDITARY DISEASES and METABOLISM, INBORN ERRORS are available as general concepts.Health Behavior: Behaviors expressed by individuals to protect, maintain or promote their health status. For example, proper diet, and appropriate exercise are activities perceived to influence health status. Life style is closely associated with health behavior and factors influencing life style are socioeconomic, educational, and cultural.Behavior: The observable response of a man or animal to a situation.Infant Nutritional Physiological Phenomena: Nutritional physiology of children from birth to 2 years of age.Infant, Very Low Birth Weight: An infant whose weight at birth is less than 1500 grams (3.3 lbs), regardless of gestational age.Sexual Behavior: Sexual activities of humans.Infant, Low Birth Weight: An infant having a birth weight of 2500 gm. (5.5 lb.) or less but INFANT, VERY LOW BIRTH WEIGHT is available for infants having a birth weight of 1500 grams (3.3 lb.) or less.Sexual Behavior, Animal: Sexual activities of animals.Exploratory Behavior: The tendency to explore or investigate a novel environment. It is considered a motivation not clearly distinguishable from curiosity.Breast Feeding: The nursing of an infant at the breast.Adolescent Behavior: Any observable response or action of an adolescent.Infant Welfare: Organized efforts by communities or organizations to improve the health and well-being of infants.Child Behavior Disorders: Disturbances considered to be pathological based on age and stage appropriateness, e.g., conduct disturbances and anaclitic depression. This concept does not include psychoneuroses, psychoses, or personality disorders with fixed patterns.Behavior Therapy: The application of modern theories of learning and conditioning in the treatment of behavior disorders.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Infant, Extremely Low Birth Weight: An infant whose weight at birth is less than 1000 grams (2.2 lbs), regardless of GESTATIONAL AGE.