| Teratogens | Effects of Exposure on Fetus | Measures for Preventing Damage |
|---|---|---|
| Diseases | ||
| Rubella (German measles) | In embryonic period, causes blindness and deafness; in first and second trimesters, causes brain damage. | Get immunized before becoming pregnant. |
| Toxoplasmosis | Brain damage, loss of vision, intellectual disabilities. | Avoid eating undercooked meat and handling cat feces, garden dirt during pregnancy. |
| Measles, chicken pox, influenza | May impair brain functioning. | Get immunized before getting pregnant; avoid infected people during pregnancy. |
| Syphilis | Baby is born with syphilis, which, untreated, leads to brain and bone damage and eventual death. | Early prenatal diagnosis and treatment with antibiotics. |
| AIDS | Baby may catch the virus. Without treatment, illness and death are likely during childhood. | Prenatal drugs and Caesarean birth make AIDS transmission rare. |
| Other sexually transmitted infections, including gonorrhea and chlamydia | Not usually harmful during pregnancy but may cause blindness and infections if transmitted during birth. | Early diagnosis and treatment; if necessary, Caesarean section, treatment of newborn. |
| Infections, including infections of urinary tract, gums, and teeth | May cause premature labour, which increases vulnerability to brain damage. | Get infection treated, preferably before becoming pregnant. |
| Pollutants | ||
| Lead, mercury, PCBs (polychlorinated biphenyls); dioxin; and some pesticides, herbicides, and cleaning compounds | May cause spontaneous abortion, preterm labour, and brain damage. | Most common substances are harmless in small doses, but pregnant women should avoid regular and direct exposure, such as drinking well water, eating unwashed fruits or vegetables, using chemical compounds, and eating fish from polluted waters. |
| Radiation | ||
| Massive or repeated exposure to radiation, as in medical X-rays | In the embryonic period, may cause abnormally small head (microcephaly) and intellectual disabilities; in the fetal period, suspected but not proven to cause brain damage. Exposure to background radiation, as from power plants, is usually too low to have an effect. | Get sonograms, not X-rays, during pregnancy; pregnant women who work directly with radiation need special protection or temporary assignment to another job. |
| Social and Behavioural Factors | ||
| Very high stress | Early in pregnancy, may cause cleft lip or cleft palate, spontaneous abortion, or preterm labour. | Get adequate relaxation, rest, and sleep; reduce hours of employment; get help with housework and child care. |
| Malnutrition | When severe, may interfere with conception, implantation, normal fetal development, and full-term birth. | Eat a balanced diet (with adequate vitamins and minerals, including, especially, folic acid, iron, and vitamin A); achieve normal weight before getting pregnant, then gain 10–15 kg during pregnancy. |
| Excessive, exhausting exercise | Can affect fetal development when it interferes with pregnant woman’s sleep, digestion, or nutrition. | Get regular, moderate exercise. |
| Medicinal Drugs | ||
| Lithium Tetracycline Retinoic acid Streptomycin ACE inhibitors Phenobarbital Thalidomide | Can cause heart abnormalities. Can harm teeth. Can cause limb deformities. Can cause deafness. Can harm digestive organs. Can affect brain development. Can stop ear and limb formation. | Avoid all medicines, whether prescription or over-the-counter, during pregnancy unless they are approved by a medical professional who knows about the pregnancy and is aware of the most recent research. |
| Psychoactive Drugs | ||
| Caffeine | Normal use poses no problem. | Avoid excessive use: Drink no more than three cups a day of beverages containing caffeine (coffee, tea, cola drinks, hot chocolate). |
| Alcohol | May cause fetal alcohol syndrome (FAS) or fetal alcohol effects (FAE). | Stop or severely limit alcohol consumption during pregnancy; especially dangerous are three or more drinks a day or four or more drinks on one occasion. |
| Tobacco | Reduces birth weight, increases risk of malformations of limbs and urinary tract, and may affect the baby’s lungs. | Stop smoking before becoming pregnant; if already pregnant, stop smoking immediately. |
| Marijuana | Heavy exposure may affect the central nervous system; when smoked, may hinder fetal growth. | Avoid or strictly limit marijuana consumption. |
| Heroin | Slows fetal growth and may cause premature labour; newborns with heroin in their bloodstream require medical treatment to prevent the pain and convulsions of withdrawal. | Get treated for heroin addiction before becoming pregnant; if already pregnant, gradual withdrawal on methadone is better than continued use of heroin. |
| Cocaine | May cause slow fetal growth, premature labour, and learning problems in the first years of life. | Stop using cocaine before pregnancy; babies of cocaine-using mothers may need special medical and educational attention in their first years of life. |
| Inhaled solvents (glue or aerosol) | May cause abnormally small head, crossed eyes, and other indications of brain damage. | Stop sniffing inhalants before becoming pregnant; be aware that serious damage can occur before a woman knows she is pregnant. |
| Sources: Gupta, 2011; Mann & Andrews, 2007; O’Rahilly & Müller, 2001; Reece & Hobbins, 2007; Sadler, 2012; Shepard & Lemire, 2004. | ||
| * The field of toxicology advances daily. Research on new substances begins with their effects on nonhuman species, which provides suggestive (though not conclusive) evidence. This table is a primer; it is no substitute for careful consultation with a professional who knows the recent research. | ||