Fetal Environmental Toxins
Lewis B. Holmes MD1
1 Chief, Embryology-Teratology Unit, Children's Service, Massachusetts General Hospital; Professor of Pediatrics, Harvard Medical School, Boston, MA.
The pediatrician often is asked by concerned parents whether their child's medical problems could be due to some type of exposure during pregnancy. Unfortunately, there seems to be an endless number of new and disturbing possibilities, such as video display terminals and electromagnetic fields, which are suggested regularly in newspaper articles, magazines, and the television news to be harmful. Experience has shown that many of these possibilities are false alarms, but much work is required before reassuring evidence becomes available. This review will summarize the current knowledge of "fetal environmental toxins" or human teratogens—terms that encompass an exposure during pregnancy that has a harmful effect on the developing fetus.
Many different types of fetal environmental toxins have been identified (Table), including:
• drugs taken by the pregnant woman,
• infections during pregnancy,
• maternal diseases,
• hypoxia,
• heat, and
• heavy metals.
The pediatrician evaluating the child who is reported to have had a harmful exposure in utero should be aware of the variety of potential effects of these exposures, including:
• spontaneous abortion;
• growth retardation, before and/or after birth;
• microcephaly;
• distinctive patterns of major and minor malformations;
• isolated major malformations;
• metabolic dysfunction, such as the diabetes mellitus that occurs in 30% of adults who had congenital rubella syndrome1;
• cognitive dysfunction;
• mental retardation;
