Birth Defects

Birth defects are conditions that are present at birth. They cause structural changes in one or more parts of the body, and may have serious adverse effects on health, development, or functional ability.  Today, researchers have identified thousands of different birth defects; some are fatal. In Louisiana, birth defects – along with prematurity - are a leading cause of death in infants (infant mortality).  According to the Centers for Disease Control and Prevention (CDC), about 3% of babies in the United States- 1 out of every 33 - is born with a structural birth defect.  Meaning that of the approximate 62,000 babies born each year in Louisiana, at least 1,800 are born with a birth defect. 

For some birth defects, such as fetal alcohol syndrome, the cause is known, but for most birth defects, the exact cause remains unknown. Currently most birth defects are understood to result from family traits (genetic), parent health and behavior, and/or our environment. It is not well understood how birth defects may be related to exposure to environmental hazards, such as chemicals, air pollution, and radiation, and these remain under study. New research explores the possible connection between exposure to specific environmental hazards and potential increases in the risk of certain birth defects.  Birth defects surveillance efforts are expanding. Data compilation, data sharing and transparency, and data query and visualization tools are also improving.  The CDC Tracking and Louisiana Department of Health (LDH) Tracking Health Data Portals have been built to assist health officials, analysts and researchers to apply the available data to better understand the relationship between birth defects and the environment.


Tracking Birth Defects in Louisiana

Measures of birth defects prevalence were developed following the CDC Standards for Nationally Consistent Data and Measures (NCDMs) within the Environmental Public Health Tracking Network. The purpose of NCDMs is to ensure compatibility and comparability of data and measures across and within states, and for the US. They allow for consistency in data use, quality, and interpretation.  Applying common data standards makes it possible to find associations and explore trends that may be present in the data, which is useful for better understanding the impact of our environment on our health.

The Health Data Explorer contains data on the prevalence of the following birth defects, displayed per 10,000 live births, for 5 year reporting periods, for children up to the age of three years.  See ‘Additional Info’ below for direct links to the CDC website with more in-depth descriptions and information on these birth defects:



Anencephaly is a rare type of neural tube defect in which a baby is born without parts of the brain and skull.  The neural tube is a narrow channel that folds and closes during the third and fourth weeks of pregnancy to form brain and skull, spinal cord, and back bones. Anencephaly occurs when the upper part of the neural tube that forms the brain and skull does not close all the way. This results in the baby’s brain not being fully formed or often not being covered by bone or skin when the baby is born.


Cleft lip with and without Cleft Palate

Cleft lip is an opening in the upper lip that occurs when a baby’s lip does not form properly during pregnancy. The opening can be a small slit in the lip or it can be a large opening that goes through the lip into the nose. A cleft lip can be on one or both sides of the lip or in the middle of the lip. Children with cleft lip can also have cleft palate.  This happens when the roof of the mouth, or palate, does not join together completely during pregnancy.


Cleft palate without Cleft Lip

A cleft palate is an opening in the roof of the mouth, called the palate. A cleft palate does not join together completely during pregnancy. For some babies, both the front and back parts of the palate are open. For other babies, only part of the palate is open.


Down Syndrome (Trisomy 21)

Down syndrome, also known medically as Trisomy 21, is a condition in which a baby is born with an extra chromosome. Chromosomes are small, threadlike structures found in the nucleus of cells that carry genetic information in the form of genes. Normally, a baby is born with 23 pairs (46 total) chromosomes.  Babies born with Down syndrome have an extra copy of chromosome 21. This extra copy or piece changes how the baby’s body and brain develop, which causes mental and physical challenges. No one knows for sure why Down syndrome occurs, but one factor that increases the risk for having a baby with Down syndrome is a mother’s age. Women who are 35 years or older when they become pregnant are more likely to have a pregnancy affected by Down syndrome.



Gastroschisis is a birth defect of the abdominal wall that causes a portion of the intestine to protrude outside of the baby’s body through an opening beside the belly button. The opening can be small or large. Sometimes other organs, such as the stomach and liver, also protrude outside of the baby’s body. Gastroschisis occurs early during pregnancy when the muscles that make up the baby’s abdominal wall do not form correctly.


Hypoplastic Left Heart Syndrome

Hypoplastic left heart syndrome is a type of congenital heart defect that affects normal blood flow through the heart. It occurs when the left side of the baby’s heart does not form correctly.



Hypospadias is a birth defect in boys where the opening of the urethra is not located at the tip of the penis. In boys with hypospadias, the urethra forms abnormally during weeks 8-14 of pregnancy. The abnormal opening can form anywhere from just below the end of the penis to the scrotum.


Upper and Lower Limb Deficiencies

Upper limb deficiencies occur when a part of, or the entire, arm of a fetus fails to form completely during pregnancy. Lower limb deficiencies occur when a part of, or the entire leg, of a fetus fails to form completely during pregnancy. These defects are also referred to as “limb reduction” because a limb is reduced from its normal size or is missing.


Spina Bifida (without Anencephaly)

Spina bifida is a neural tube defect that can happen anywhere along the spine when the neural tube does not close all the way. It may be, but is not always apparent at birth. In Spina Bifida without Anencephaly, the backbone that protects the spinal cord does not form and close as it should, which results in damage to the spinal cord and nerves.


Tetralogy of Fallot

Tetralogy of Fallot is a type of congenital heart defect affecting normal blood flow through the heart that occurs when a baby’s heart does not form correctly. Tetralogy of Fallot is a combination of as many as four defects: a hole in the wall between the two lower chambers of the heart; a narrowing of the pulmonary valve and main pulmonary artery; an enlarged aortic valve that opens from both ventricles; or the muscular wall of the lower right chamber of the heart is thicker than normal.


Transposition of the Great Arteries (vessels)

Transposition of the Great Arteries is a congenital heart defect that occurs when the two main arteries that carry blood out of the heart - the aorta and the pulmonary artery - are switched in position.


Data Sources

LDH Louisiana Birth Defects Monitoring Network



Additional Info

CDC Birth Defects Info