Pacifier Use

A pacifier is an artificial nipple designed for babies to suck on for comfort.


Pain is an unpleasant feeling that is conveyed to the brain by nerves in the body.

Pain Management

Pain management covers a number of methods to prevent, reduce, or stop pain sensations. These include the use of medications; physical methods such as ice and physical therapy; and psychological methods.

Parent-Child Relationships

The parent-child relationship consists of a combination of behaviors, feelings, and expectations that are unique to a particular parent and a particular child. The relationship involves the full extent of a child's development.

Patau Syndrome

Patau syndrome, also called trisomy 13, is a congenital (present at birth) disorder associated with the presence of an extra copy of chromosome 13. The extra chromosome 13 causes numerous physical and mental abnormalities, especially heart defects.

Patent Ductus Arteriosus

Patent ductus arteriosus (PDA) is a heart defect that occurs in infants when the ductus arteriosus (the temporary fetal blood vessel that connects the aorta and the pulmonary artery) does not close at birth.

Peer Acceptance

Peer acceptance is the degree to which a child or adolescent is socially accepted by peers. It includes the level of peer popularity and the ease with which a child or adolescent can initiate and maintain satisfactory peer relationships.

Peer Pressure

Peer pressure is the influence of a social group on an individual.


Penicillins are a group of closely related antibiotics that kill bacteria.

Perforated Eardrum

A perforated eardrum (tympanum perforation) is an opening or rupture in the eardrum (tympanic membrane), the thin membrane that separates the outer ear canal from the middle ear. A perforated eardrum may be caused by infection, trauma, or negative pressure from underwater diving or an airplane flight.

Perinatal Infection

An infection caused by a bacteria or virus that can be passed from a mother to her baby during pregnancy or delivery is called a perinatal infection.

Periodontal Disease

Periodontal diseases are a group of diseases that affect the tissues that support and anchor the teeth. Left untreated, periodontal disease results in the destruction of the gums, alveolar bone (the part of the jaws where the teeth arise), and the outer layer of the tooth root.

Peroxisomal Disorders

Peroxisomal disorders are a group of congenital diseases characterized by the absence of normal peroxisomes in the cells of the body.

Personality Development

Personality development is the development of the organized pattern of behaviors and attitudes that makes a person distinctive. Personality development occurs by the ongoing interaction of temperament, character, and environment.

Personality Disorders

Personality disorders (PD) are a group of psychiatric conditions characterized by experience and behavior patterns that cause serious problems with respect to any two of the following: thinking, mood, personal relations, and the control of impulses.

Pervasive Developmental Disorders

Pervasive developmental disorders are a group of neurological disorders that include autistic disorder (autism), Asperger's syndrome, childhood disintegrative disorder, Rett's syndrome, and pervasive developmental disorder not otherwise specified (PDDNOS). These disorders are characterized by delayed development in functional, socialization, and communication skills.


Phenylketonuria (PKU) is a rare metabolic disorder caused by a deficiency in the production of the hepatic (liver) enzyme phenylalanine hydroxylase (PAH).


A phobia is an intense and unrealistic fear brought on by an object, event, or situation, which can interfere with the ability to socialize, work, or go about everyday life.


Pica is the persistent craving and compulsive eating of non-food substances.

Piercing and Tattoos

Body piercing and tattoos are forms of body art that have been practiced throughout history by various cultures.


Pinta is a bacterial infection of the skin that causes lesions, red to bluish-black colored spots and splotches, and discoloration of the skin.


Pinworms, Enterobius vermicularis, are small, white worms that can live in the intestines, are common in young children, and are easily treated.

Pituitary Dwarfism

Dwarfism is a condition in which the growth of the individual is very slow or delayed, resulting in less than normal adult stature. The word pituitary refers to the pituitary gland, which regulates the production of certain chemicals called hormones.

Pityriasis Rosea

Pityriasis rosea is a mild skin disorder common among children and young adults, manifesting initially as a single round spot on the body and followed later by a rash of colored spots on the body and upper arms.

Platelet Count

A platelet count is a diagnostic test that determines the number of platelets in the patient's blood. Platelets, which are also called thrombocytes, are small disk-shaped blood cells produced in the bone marrow and involved in the process of blood clotting.


Play is the work of children. It consists of those activities performed for self-amusement that have behavioral, social, and psychomotor rewards.


Pneumonia is an infection of the lungs that can be caused by nearly any class of organism known to cause human infections, including bacteria, viruses, fungi, and parasites. It results in an inflammatory response within the small air spaces of the lung (alveoli).

Poison Ivy, Oak, and Sumac

Poison ivy, oak, and sumac are allergic skin rashes (or Rhus dermatitis) caused by the plants of the same name. All three plants secrete a potent, irritating oil known as urushiol that causes blistering and intense itching once it penetrates the skin.


Poisoning occurs when any substance interferes with normal body functions after it is swallowed, inhaled, injected, or absorbed. The branch of medicine that deals with the detection and treatment of poisons is known as toxicology.


Poliomyelitis, also called polio or infantile paralysis, is a highly infectious viral disease that may attack the central nervous system and is characterized by symptoms that range from a mild nonparalytic infection to total paralysis in a matter of hours.

Polio Vaccine

The poliomyelitis (polio) vaccine protects against poliovirus infections. The vaccine helps the body produce antibodies (protective substances) that will prevent an individual from contracting polio.

Polydactyly and Syndactyly

Polydactyly and syndactyly are congenital malformations of the fingers and/or toes. Polydactyly is the presence of extra fingers or toes, and syndactyly is the fusing together or webbing of two or more fingers or toes.


The porphyrias are disorders in which the body produces too much porphyrin and insufficient heme (an iron-containing nonprotein portion of the hemoglobin molecule). Porphyrin is a foundation structure for heme and certain enzymes.

Post-Concussion Syndrome

Post-concussion syndrome (PCS) is a common but controversial disorder with a variety of symptoms including, but not limited to, headache, dizziness, fatigue, and personality changes.

Prader-Willi Syndrome

Prader-Willi syndrome (PWS) is a genetic condition caused by the absence of chromosomal material from chromosome 15. Characteristics of the syndrome include developmental delays, poor muscle tone, short stature, small hands and feet, incomplete sexual development, and unique facial features.

Precocious Puberty

Precocious puberty is sexual development before the age of eight in girls, and age 10 in boys.


The average length of a normal pregnancy is 40 weeks (280 days) from the date of conception. Infants born before 37 weeks gestation are considered premature and may be at risk for complications.

Premenstrual Syndrome

Premenstrual syndrome (PMS) refers to symptoms that occur between ovulation and the onset of menstruation. The symptoms include both physical symptoms, such as breast tenderness, back pain, abdominal cramps, headache, and changes in appetite, and psychological symptoms of anxiety, depression, and unrest.

Prenatal Development

Prenatal development refers to the process in which a baby develops from a single cell after conception into an embryo and later a fetus.

Prenatal Surgery

Prenatal surgery is a surgical procedure performed on a fetus prior to birth.


Preschool is an early childhood program in which children combine learning with play in a program run by professionally trained adults. Children are most commonly enrolled in preschool between the ages of three and five, though those as young as two can attend some schools.

Prickly Heat

Prickly heat is also known as sweat retention syndrome or miliaria rubra. It is a common disorder of the sweat glands.

Protein-Energy Malnutrition

Protein-energy malnutrition (PEM) is a potentially fatal body-depletion disorder. It is the leading cause of death in children in developing countries.


Named for the Greek word psōra meaning itch, psoriasis is a chronic, non-contagious disease characterized by inflamed lesions covered with silvery-white scabs of dead skin.

Psychological Tests

Psychological tests are written, visual, or verbal evaluations administered to assess the cognitive and emotional functioning of children and adults.

Psychosocial Personality Disorders

A psychosocial disorder is a mental illness caused or influenced by life experiences, as well as maladjusted cognitive and behavioral processes.


Puberty is the period of human development during which physical growth and sexual maturity occurs.

Pulmonary Function Tests

Pulmonary function tests are a group of procedures that measure how well the lungs are functioning.