Most women encounter a variety of chemical and environmental exposures during their pregnancy. Many of these exposures may be harmless, but some may have adverse effects on a developing baby. Although we lack reliable information about the effects of most chemicals on pregnancy and neonatal health outcomes, pregnant women are encouraged to minimize potential risks by avoiding or limiting exposure to chemical substances. This includes avoiding fumigation, which is the use of gas pesticides to kill insects, such as termites and cockroaches, weeds, rodents, or fungi. The gases, called fumigants, contain chemicals that disrupt a variety of normal functions, including biochemical processes, hormonal signals, and nervous system activity in the pest that is being targeted. However, rather than only affecting the target, these gases may also harm people exposed through skin contact, inhalation, or accidental intake. This is particularly concerning for an expectant mother and her developing fetus.
Moms exposed to fumigation may develop a number of troubling symptoms, such as nausea, diarrhea, vomiting, breathing difficulties, confusion, muscle tremors or convulsions. High levels or persistent pesticide exposure may elicit worse symptoms, causing organ damage in the liver and kidneys, and reduced fertility. When Mom is exposed to a poison, her developing baby is also at risk. Some of the risks associated with fumigation during pregnancy include the following.
- Neurological defects. Major fetal organ development occurs during the first trimester, making this an especially vulnerable period. Exposure to harmful chemicals during early pregnancy could affect fetal nervous system development, because the neural tube forms between weeks 3 and 8. There are links between pesticide exposure and behavioral problems, attention-deficit hyperactivity disorder, cognitive impairments, motor defects, developmental delays, and autism. One study from the University of California, Davis, reported that one-third of pregnant women who lived within a mile of a documented commercial fumigation had a 60% increased risk of having a child who developed an autism spectrum disorder or developmental delay depending on the type of pesticides used. However, these are correlative studies and not conclusive of true cause and effect. Some evidence suggests that pesticide exposure may trigger mutations or work in tandem with underlying genetic risk factors to cause neurological conditions, such as autism, which may explain why some newborns or children do not present symptoms, whereas others do, despite encountering similar environmental factors. There are also studies that do not support an effect of gestational fumigant exposure on impaired cognitive abilities, demonstrating the need for further, in-depth investigation.
- Preterm birth or miscarriage. The risk of miscarriage from pesticides remains controversial, with some studies refuting and some supporting a correlation. Investigators in California showed that women who lived within two miles of farms that were fumigated during the first two months of pregnancy had an increased risk of developing fetal defects and miscarriage. The risk was even higher for women living within a mile of the fumigation zone. There are also data suggesting a higher risk of premature birth and delivery of low-weight babies if mothers lived close to agricultural areas that received fumigation with pesticides. Occupational exposure to pesticides, which may occur in agricultural professions, can also influence pregnancy outcomes. Protective clothing and environmental safety precautions should be discussed with employers in these cases. In contrast to the studies discussed above, a recent study reported the absence of any association between pesticide exposure and preterm birth, suggesting the need for follow-up studies, including if there are predisposing genetic or biological factors that increase the risk of adverse effects from pesticides.
- Childhood cancers. Limited data link exposure to indoor but not outdoor pesticides during pregnancy with the development of certain forms of childhood blood cancers. However, these studies do not always consider other potential risk factors, such as lifestyle or underlying biological makeup.
Current data linking fumigation to adverse effects on pregnancy and childhood health are mostly correlative. In addition, there are studies supporting and studies refuting these associations. Some considerations that have not been adequately addressed include the effects of chemical mixtures on pregnancy, since chemicals are not encountered as single agents in the real world, but rather as mixtures of chemicals. Further, we need a clearer understanding of acute versus chronic exposures on maternal and neonatal health. Despite potential controversies about the associations between fumigation and pregnancy health outcomes, the safest approach for a pregnant woman is to avoid or minimize exposure to pesticides whenever possible.
