Birth Defects

It is not clear how many birth defects are related to environmental exposures such as chemicals, drugs, and radiation. Some endocrine-disrupting chemicals including polychlorinated biphenyls (PCBs), dioxins, and pesticides, have been linked to nervous system defects and developmental problems such as reduced muscle tone and response. More data is needed to make these connections clearer.

Living near a hazardous waste site has been identified as a possible risk factor for birth defects such as neural tube defects, which affect the developing brain and spinal cord.

Exposure to disinfection by-products in drinking water such as trihalomethanes (THM) may increase the risk of some types of birth defects that affect the brain and spinal cord, the urinary tract, and the heart.

Other environmental factors suspected to be associated with birth defects include arsenic, plastics, solvents, and mercury.

The baby's development may be more susceptible to environmental exposures during the first trimester. This is the most sensitive time in pregnancy, when the organs and limbs are formed.

The Health Department is authorized by law to collect information for the Vermont Birth Information Network (BIN). The BIN currently collects information about more than 40 birth conditions. Twelve of these conditions are included in the Vermont Tracking portal.

The following 12 birth defects that are part of the Tracking portal:

• Anencephaly

• Spina Bifida (without Anencephaly)

• Hypoplastic Left Heart Syndrome

• Tetralogy of Fallot

• Transposition of the Great Arteries (Vessels)

• Cleft Lip with Cleft Palate

• Cleft Lip without Cleft Palate

• Cleft Palate without Cleft Lip

• Hypospadias

• Gastroschisis

• Down Syndrome (Trisomy 21)

• Limb Deficiencies Combined

Data about birth defects on the Vermont Tracking portal are for live births and for birth conditions diagnosed on or before the baby’s first birthday.

The data are presented in five year periods starting in 2006 (with Limb Deficiencies starting in 2010). Data includes the number of babies with the birth defect, the average annual number of cases over the five-year period, and the prevalence rate per 10,000 live births. For Hypospadias, prevalence rates are calculated per 10,000 male live births.

Even with five years of data, numbers of birth conditions in Vermont are small. When numbers of cases are fewer than six, the Vermont Tracking portal does not show exact counts. With fewer than six cases, it is almost impossible to tell random changes from true changes in the data. Reporting small numbers is also avoided to maintain the confidentiality of individuals.

The Vermont Birth Information Network (BIN) monitored 33 birth defects from 2008 to 2012, with an additional two conditions (upper limb reduction and lower limb reduction) added in 2010. Only structural and chromosomal birth defects monitored by the BIN are included in the following statistics. From 2008 to 2012, 2.6% of all infants born to Vermont mothers had at least one birth defect monitored by the BIN. From 2008 to 2012, 24% of all infants born with birth defects to Vermont mothers had more than one birth defect monitored by the BIN.