| Maternal Exposure / Physical Agents |
IONIZING RADIATION
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Acute large-dose radiation has no effect nor is it lethal to the embryo during the pre-implantation stage. During the period of embryogenesis it causes microcephaly mental and growth retardation.
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The risk is greatest at 8-15 weeks of gestation.
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Continuous chronic low dose exposure of less than 5rad has no adverse effects.
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There is an association between in utero exposure to diagnostic radiation and childhood leukemia.
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Video Display Terminals (VDT) has no adverse reproductive outcomes.
HYPERTHERMIA, PYREXIA
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May cause neural tube defects in the fetus.
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May cause abortions, intrauterine death or preterm labor.
ORGANIC MERCURY- METHYL MERCURY
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Maternal poisoning causes fetal neurologic damage with psychomotor retardation, seizures, cerebral palsy, blindness and deafness.
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Low-level methyl mercury exposure may cause chromosomal abnormalities in the embryo; and has been shown to be lethal in animals at high doses causing structural malformations such as exencephaly and limb deformities.
ELEMENTAL MERCURY (VAPOR)
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Chronic exposure to high doses (more than 0.01 mg/m3) can cause cranial defects and fetal resorption in animals.
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Limited human data available, but possible association present between chronic exposure to high doses with abortions and brain damage to the fetus.
LEAD
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Lead concentration in the blood should not exceed 25meg/dL in women of reproductive age and should be less than 10 mg/dL in pregnant women, to ensure no adverse effects to the fetus. Women should not work in areas where lead concentration in the air reaches 50 meg/cm3.
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Exposure to high levels can cause embryotoxicity, growth and mental retardation, abortions, premature rupture of membranes, preterm deliveries, neurologic impairment (attention deficit disorders, hearing deficit, learning disabilities) and short stature.
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Prenatal lead exposure may cause impaired mental development.
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Mothers exposed to high lead levels should avoid breast feeding.
ORGANIC SOLVENTS INCLUDING TOLUENE
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Maternal solvent abuse by sniffing may cause embryopathy similar to fetal alcohol syndrome.
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Occupational exposure to organic solvent may cause spontaneous abortions.
ANESTHETIC GASES
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Women chronically exposed to anesthetic gases in the 1st trimester are at increased risk to spontaneous abortions.
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Maternal exposure to anesthetic gases increases the risk of congenital anomalies (Spina bifida).
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Chronic exposure to unscavenged nitrous oxide may reduce fertility and increase the risk of spontaneous abortion.
SMOKING
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Associated with:
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Small for date babies
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Prematurity
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Increase in rate of spontaneous abortion and increase in perinatal mortality due to an increased risk of abruption, placenta previa and premature rupture of membranes.
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Passive smoking is also associated with low birth weight at term.
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Associated with sudden infant death syndrome.
