Functional vs Structural Defects

Functional defects affect 1 in 3,500 babies and usually involve a missing or incorrectly formed enzyme (a protein necessary for processing chemical substances in the body). This type of defect can be harmful or even fatal. Functional defects include Tay-Sachs disease, and phenylketonuria (PKU).

Structural defects are those that result when a specific body part is missing or formed incorrectly or when there is an inborn problem in body chemistry. The most common type of major structural defects are heart defects, which affect 1 in 100 babies in the United States.

Causes

Most babies with birth defects are born to two parents with no obvious health problems or risk factors. A woman can do everything her doctor recommends to deliver a healthy child and still have a baby with a birth defect because over 60% of birth defects have no known causes. The other 40% are caused by genetics and environmental factors.

Environmental causes of birth defects have more to do with the mother's health and her exposure to chemicals or diseases. When a mother has certain infections or ingests certain substances it can cause birth defects.

Genetics are also a major influence of birth defects. The number or structure of chromosomes the baby is given will effect if it has a defect. Boys are more likely to gain genetic birth defects because they have only the one X chromosome they receive from their mothers (females have two X chromosomes — one from each parent), a faulty gene on the X chromosome they receive will cause problems because they don't have another X chromosome that females have to correct it.

What is a birth defect?

Birth defects are defined as abnormalities of structure, function, or body metabolism that are present at birth. These abnormalities lead to mental or physical disabilities or are fatal. There are more than 4,000 different known birth defects, ranging from minor to serious, and although many can be treated or cured, they're the leading cause of death in the first year of life.