Types of Teratogens

Teratogens can lurk in your house, garden, medicine cabinet, and even inside your body. Knowing what these dangerous agents are is the first step to protecting yourself and your baby.

Alcohol
Wine, beer, and all other types of alcohol can harm a baby during pregnancy. Alcohol passes through the umbilical cord to a developing baby and can cause stillbirth and miscarriage. Alcohol can also create a lifelong spectrum of physical, behavioral, and intellectual disorders known as fetal alcohol syndrome
Smoking Cigarettes
Smoking cigarettes negatively impacts fertility, increases the risk for pregnancy complications like stillbirth and miscarriage, and is linked to several birth defects. Specifically, smoking can damage fragile, growing tissue in a developing baby's lungs and brain.2

The risks of using nicotine-containing e-cigarettes and vaping devices during pregnancy aren't fully known. However, early research suggests that exposure to nicotine in the womb can cause damage to babies' developing cardiovascular, immune, nervous, and respiratory systems, even in the absence of tobacco smoke.6

Recreational Drugs
About 1 in 20 pregnant people takes street drugs like marijuana, cocaine, and heroin during pregnancy, which is very harmful to fetal development. These drugs are linked to infertility, premature birth, miscarriage, low birth weight, and birth defects.7

Certain Medications
Even some doctor-approved medications can be harmful as soon as you conceive. Neurological drugs, like antiepileptic medications, can cause cognitive defects in babies, and blood thinners are linked to certain congenital malformations. Accutane, retinoids, and other skincare medications containing vitamin A can cause serious abnormalities, including cleft palates and intellectual disabilities.5

Some Infections
A pregnant person's exposure to some viruses, bacteria, and parasites can pose harm to the baby. Some of the more dangerous infections are grouped under the acronym TORCH:8

Toxoplasma (often passed through cat feces)
Rubella (German measles)
Cytomegalovirus
Herpes simplex virus
The risk of some infections is higher in certain geographic regions. Since 2015, when there was an outbreak of the mosquito-borne Zika virus throughout Central and South America and parts of the southern United States, 10% of babies born in the U.S. to mothers with an active Zika infection during pregnancy had birth defects.9

Flu is not linked to birth defects, but the high fevers it can bring on are. Pregnant people with COVID-19 are at higher risk for health problems like preeclampsia and infections, and their babies are more likely to be born prematurely.10

Harmful Physical Agents
Even in the womb, babies are sensitive to some invisible environmental forces. These include radiation, like from x-rays, or heat sources that cause your temperature to exceed 102 degrees Fahrenheit for a prolonged period, such as excessive hot tub use or a high fever.5

Toxic Chemicals and Substances
Pregnant people are often inadvertently exposed to toxic chemicals in certain workplaces like industrial factories, dry-cleaning facilities, and medical offices. Some dangerous substances that are used in these workplaces include heavy metals, organic solvents, and petrochemicals.11

Excessive exposure to household lead (like in old paint and construction) and dietary mercury (found in tuna and other big fish) are also known to cause neurological issues and cognitive delays.12

Maternal Health Problems
You can have a physical condition yourself that can hamper fetal development, which is one reason your health should be closely monitored before and during pregnancy. For example, untreated diabetes can cause miscarriage, stillbirth, and fetal abnormalities.13 Babies born to parents with unchecked thyroid issues can have lower IQs and motor skill problems.14
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