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multiple birth

(Encyclopedia)multiple birth, bringing forth of more than one offspring at birth. Although many smaller mammals bear several young at a time, multiple births are relatively uncommon in humans and other primates. Tw...

birth

(Encyclopedia)birth or labor, delivery of the fetus by the viviparous mammal. Birth is also known as parturition. Human birth normally occurs about 280 days after onset of the last menstrual period before conceptio...

multiple personality

(Encyclopedia)multiple personality, a very rare psychological disorder in which a person has two or more distinct personalities, each with its own thoughts, feelings, and patterns of behavior. The personalities oft...

multiple sclerosis

(Encyclopedia)multiple sclerosis (MS), chronic, slowly progressive autoimmune disease in which the body's immune system attacks the protective myelin sheaths that surround the nerve cells of the brain and spinal co...

birth control

(Encyclopedia)birth control, practice of contraception for the purpose of limiting reproduction. Although contraceptive techniques had been known in ancient Egypt, Greece, and Rome, the modern movement for birth ...

birth defects

(Encyclopedia)birth defects, abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs...

birth rate

(Encyclopedia)birth rate: see vital statistics. ...

multiple chemical sensitivity

(Encyclopedia)multiple chemical sensitivity (MCS), adverse physical reaction to certain chemicals in susceptible persons. When exposed to the chemicals, people with MCS react with symptoms such as nausea, headache,...

twins

(Encyclopedia)twins: see multiple birth.

law of simple multiple proportions

(Encyclopedia)law of simple multiple proportions, in chemistry, the statement that when two or more elements form more than one compound, the ratio of the weights of one element that combine with a given weight of ...