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Relationship of Birth Defects to the Environment

Pesticides and Gastroschisis
Pesticides are chemicals used to control insects, weeds, fungus, and other pests. According to the March of Dimes, pregnant women should avoid exposure to pesticides whenever possible.  Pesticides are commonly used in or around:

Research suggests that a woman’s exposure to atrazine, an herbicide used to eliminate weeds in agricultural areas, could be associated with gastroschisis. Gastroschisis is a birth defect of the intestines. Prenatal exposure to higher concentrations of atrazine in surface water (lakes, ponds, rivers, etc.), may increase the prevalence of gastroschisis, especially among women who conceived in the spring.

Disinfection Byproducts
Disinfection byproducts come from chemicals used in our drinking water to kill microorganisms such as bacteria and viruses. Exposure to disinfection byproducts in drinking water, such as trihalomethanes (THM), may increase the risk for birth defects that affect development of the brain, spinal cord, urinary tract and heart.

Arsenic
Arsenic is a toxic element that occurs naturally in the environment and as a byproduct of some industrial activities. Pregnant women who are exposed to high levels of arsenic can be at risk for having a baby born with birth defects.

People are at greater risk for arsenic exposure if they:

Plastics
Two chemicals found in plastics – Bisphenol A and phthalates – have raised concerns over their potential link to birth defects. Bisphenol A (BPA) is used to manufacture polycarbonate plastic and epoxy resins. BPA may affect brain, behavior and prostate gland development in fetuses, infants, and children. Phthalates are found in higher concentrations in children than in adults. Research indicates that phthalates may increase the risk of birth defects such as hypospadias.

BPA is found in the epoxy resins used to line:

Phthalates are added to make plastics more flexible and durable. They can be found in:

Solvents
Solvents are chemicals that dissolve other substances. Exposure to solvents during pregnancy, particularly during the first trimester, may increase risk of neural tube and heart defects.

Common solvents include:

Mercury
Exposure to mercury while pregnant may harm the baby’s nervous system development. There are two forms of mercury: elemental (pure) mercury and methylmercury.

Elemental mercury is found in:

Methylmercury is formed when mercury in the air is deposited in water. People are usually exposed to this form of mercury when they eat certain fish, especially larger fish that eat smaller fish.

Examples of large fish that tend to contain large amounts of methylmercury.

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The above content was generously shared by the California Environmental Health Tracking Program. Sources include:

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Types of Birth Defects

Anencephaly is a birth defect that affects the closing of the neural tube during pregnancy. The neural tube is a narrow channel that folds and closes during the third and fourth weeks of pregnancy to form the brain and spinal cord. Anencephaly occurs when the portion of the neural tube that forms the brain does not close. This results in the baby lacking parts of the brain, skull, and scalp

Spina Bifida (without Anencephaly) is a type of neural tube defect. The neural tube is a narrow channel that folds and closes during the third and fourth weeks of pregnancy to form the brain and spinal cord. Spina bifida happens if the portion of the neural tube that forms the spinal cord does not close completely during the first month of pregnancy. 

Hypoplastic Left Heart Syndrome is a condition that is present at birth, and often is called a congenital heart defect. It is a group of related defects that, together, mean that the left side of the heart is underdeveloped.   

Tetralogy of Fallot is a heart condition that is present at birth, and often is called a congenital heart defect. This defect changes the normal flow of blood through the heart. Tetralogy of Fallot is a combination of four defects: (1) a hole in the wall between the ventricles (two lower chambers of the heart), called a ventricular septal defect; (2) narrowing of the tube that carries blood from the heart to the lungs, called pulmonary stenosis; (3) the aorta (the tube that carries oxygen-rich blood to the body) grows from both ventricles, rather than from the left ventricle only; and (4) a thickened muscular wall of the right ventricle, called right ventricular hypertrophy. 

Transposition of the Great Arteries (Vessels) is a heart condition that is present at birth, and often is called a congenital heart defect. Transposition of the great arteries occurs when the two main arteries going out of the heart – the pulmonary artery and the aorta – are switched in position, or “transposed”.

Cleft Lip (with or without Cleft Palate) is an opening in the upper lip. The opening in the lip can be a small slit in the lip or a large opening that goes through the lip into the nose. A cleft palate is an opening in the roof of the mouth, called the palate. A cleft palate can occur when the two sides of the palate do not come together correctly.

Cleft Palate (without Cleft Lip) is an opening in the roof of the mouth, called the palate. A cleft palate can occur when the two sides of the palate do not come together correctly.

Hypospadias is a birth defect of males in which the opening of the urethra is located somewhere along the underside of the penis instead of at the tip. The urethra is the tube that carries urine from the bladder to the outside of the body. This defect occurs when the urethra does not complete its development during the pregnancy.   

Gastroschisis is a birth defect in which a portion of an infant's intestines protrude out of the body through a small hole in the body wall beside the umbilical cord. The body wall defect can be small or large, and other organs such as the liver can be involved.   

Down Syndrome (Trisomy 21) is a condition in which a baby is born with an extra chromosome. Chromosomes are small “packages” of genes in the body. They determine how a baby’s body forms during pregnancy and how, as the baby grows in the womb and after birth, the body functions. Normally, a baby is born with 46 chromosomes. Babies born with Down syndrome have an extra copy of one of these chromosomes. This extra copy changes the body’s and brain’s normal development and causes developmental and physical problems for the baby.

Upper Limb Deficiencies are defects that occur when a part of or the entire arm (upper limb) of a baby fails to form completely during pregnancy. The defect is referred to as a “limb reduction” because a limb is reduced from its normal size or is missing. 

Lower Limb Deficiencies are defects that occur when a part of or the entire leg (lower limb) of a fetus fails to form completely during pregnancy. The defect is referred to as a “limb reduction” because a limb is reduced from its normal size or is missing. 

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