Birth Defects Causes

Fetal development during pregnancy takes place over the course of 40 weeks, and involves growth and development of all the fetus’ physical structures. Abnormalities in any stage of fetal development (particularly during the first few months) can lead to many rare and common birth defects. Causes can be environmental, genetic or the result of an interaction of multiple factors.

Environmental Birth Defect Causes

A birth defect can be caused by exposure to harmful substances (known as “teratogens”) during pregnancy, such as alcohol and prescription or illegal drugs. Anything a mother ingests, inhales or takes in by other methods while pregnant can be transmitted to the fetus, and can affect development.

Several factors contribute to the extent teratogens can have on development, including:

  • Developmental stage at the time of exposure
  • Interactions of other environmental or genetic factors
  • Level or duration of exposure.

Certain types of maternal illness during pregnancy can also lead to common birth defects.

Genetic Birth Defect Causes

Genetics can affect fetal development in a number of ways.

Genetic syndromes are caused by the inheritance of genes from one or both parents, and often affect multiple body systems and structures. Mutations or defects in certain chromosomes can also cause syndromes. For example, trisomy, or having three copies of a chromosome rather than the typical two copies, can lead to syndromes such as Down’s syndrome (trisomy 21) and Patau syndrome (trisomy 13). However, a chromosomal defect or genetic syndrome isn’t always considered a “birth defect.”

Congenital malformations of particular body structures that occur without a specific genetic or chromosomal mutation can also be affected by genetics. Genetic makeup inherited from parents can make a baby predisposed to a particular birth defect, such as cleft palate. However, birth defects’ causes typically depend on the interaction of genetics with environmental factors.

Idiopathic Birth Defects

Though genetics and the environment can lead to the development of a birth defect, some are idiopathic, meaning their causes are not well understood. Idiopathic birth defects are common: The March of Dimes reports that up to 70 percent of all birth defects have no known cause.

In these cases, there may be no method of preventing the birth defect. Parents should try not to feel responsible for a birth defect that could not have been avoided. However, in order to reduce chances of a birth defect, you’ll want to make healthy choices during pregnancy, such as:

  • Avoiding toxins
  • Healthy diet
  • Plenty of exercise.

Resources

Centers for Disease Control and Prevention. (n.d.). Birth defects FAQs. Retrieved April 7, 2010, from: http://www.cdc.gov/ncbddd/BD/faq2.htm.

March of Dimes. (n.d.). Birth defects: Quick reference fact sheet. Retrieved April 3, 2010, from: http://www.marchofdimes.com/professionals/14332_1206.asp#head1 .

Merck. (n.d.). Birth defects. Retrieved April 3, 2010, from: http://www.merck.com/mmhe/sec23/ch265/ch265a.html.