Catch-up Growth: Accelerated growth of small infants during the first 2 years of life, which enables them to attain a normal size. Most children born SGA will have their catch-up growth by ages 2 to 3 years, but some do not.

Chromosomes: The entire body is made of tiny units called cells. Inside each cell are 23 pairs of chromosomes. Chromosomes are linear strands made of DNA that contain a person’s genes.

Genes: Genes are the basic units of hereditary. They are located in specific places on chromosomes. Genes are made of DNA, which is a code to tell the body how to build a specific protein. All the hereditary information contained in a person is called a genotype.

Geneticist: A scientist who specializes in genetics, the study of heredity and its variants.

Genetic Mutation: A permanent change in a gene’s structure that is potentially capable of being transmitted to children.

Gestational Age: The age of a fetus in weeks, measured from the first day of a woman’s last menstrual cycle to the current date. A normal pregnancy can range from 37 to 41 weeks.

Growth Hormone: A hormone produced by the pituitary gland that is necessary for normal growth.

Growth Hormone Deficiency: A disorder in which the body does not make enough growth hormone.

Infantometer: A device used to measure length in infants and children up to 2 years of age. It consists of a firm, flat surface with an immovable headpiece and a movable footpiece, which are perpendicular to the measuring tape.

Karyotype: A representation of the chromosomes in a single cell, which are arranged in numerical order from largest to smallest.

Pediatric endocrinologist: A specialist who diagnoses and treats hormonal diseases in children.

Percentile: 1 of 100 equal divisions that indicates how much of a group is equal to or below it. For example, a percentile score of 92 is equal to or higher than 92% of other scores.

Pituitary Gland: A small, round gland located at the base of the brain. The pituitary gland produces a number of hormones, including growth hormone, which it sends via the bloodstream throughout the body to regulate growth.

Pubertal growth: The growth period related to or occurring in puberty (the period of sexual maturity).

Stadiometer: A device used to measure the height of children older than 2 years. It consists of a vertical board with an attached metric ruler and a movable horizontal headpiece.

Stature: The standing height of a person.

Stimulate: To increase activity.