Abortions, spontaneous

Embryos die for any number of reasons (e.g., degeneration of the corpus luteum or a defective trophoblast) and they are aborted spontaneously with the next menstrual period - usually without producing any of the maternal signs associated with pregnancy. Thus, by the end of the first expected menstrual period more than one-half of all human eggs exposed to sperm under the best of conditions die for one reason or another. 

Holoprosencephaly occurs in approximately 1 of 16000 live human births although the overall incidence is appreciably greater because 99% of affected embryos abort spontaneously [61]. Thus, holoprosencephaly is considerably more common in early embryogenesis, occurring in about 1 of... 

Lead is known to cause reproductive and developmental toxicity. Decreased sperm counts and abnormal sperm development have been reported in male workers heavily exposed to lead. Increased incidences of spontaneous abortion have been reported in female lead workers as well as in the wives of male lead workers (13). Lead crosses the placenta and has been found to cause irreversible neurologic impairment to the fetus at maternal blood levels as... 

There appear also to be toxic effects. In animals, nitrous oxide has been shown to inactivate methionine synthetase which prevents the conversion of deoxyuridine to thymidine and thus has the potential for inducing megaloblastic anemia, leukopenia, and teratogenicity (44—46). A variety of epidemiologic surveys suggest positive correlations between exposure to nitrous oxide and spontaneous abortion in dental assistants (47). 

This drug may cause spontaneous abortion. Women of childbearing age must use a reliable contraceptive If pregnancy is suspected, discontinue use of tiie drug and notify the primary health care provider. Report severe menstrual pain, bleeding, or spotting. 

Prevent isoimmunization of Rh (D)-negative women at the time of spontaneous or induced abortion... 

When the newborn population Is examined It Is found that between 2 and 4% of Individuals, depending on how the figures are calculated, have some type of birth defect which Is considered to be genetic In origin (8,9) The term "birth defect" Is used In a general sense and encompasses all types of structural, metabolic, and other abnormalities which derive from genetic or other prenatal causes. The birth defects detected postnatally represent only a small fraction of the totality of abnormalities which result from genetic aberrations, but most of the latter result In early spontaneous abortions... 

In these 500 cases, there were 26 culture failures, an Incidence of about 5% Nine women of this group underwent a second aminocentesls, and successful cultures were obtained The other 17, or 3 4% of the total, did not obtain any results, either because of spontaneous abortions prior to the time a second amniocentesis could be performed (In four) or because the family elected not to proceed There were no Instances of severe or significant fetal Injury, although small linear "scars" were noted on four fetuses Three fetuses had abnormalities which were not related to the procedure Itself, Including spina bifida, osteogenesis Imperfecta, and congenital heart disease ... 

One set of undetected triplets also occurred. In addition to the twins already mentioned Ten abortions occurred following amniocentesis, three occurring within one week of the procedure and associated with fever, and seven not associated with fever and occurring between 18 and 50 days after amniocentesis Itself, the former group which comprises 0 4% of the total, must be considered a direct complication However, even this conclusion must be tempered by the fact that In the week prior to a scheduled amniocentesis, 20 women had spontaneous abortions ... 

Human Spontaneous Abortions with Chromosomal Abnormalities", Aging Gametes, Int. Symp. Seattle, (1975), 330-348. 

Brucella abortus is a cause of spontaneous abortion in cattle. In humans it causes undulant fever, i.e. a fever in which temperature undulates with time. Brucella melitensis infects goats it causes an undulant fever called Malta fever, which is common in people living in Mediterranean countries where large flocks of goats are kept. 

A retrospective case-control study conducted in humans compared spontaneous abortion rates among women who had been exposed occupationally or nonoccupationally to trichloroethylene and other solvents to rates among women without solvent exposure (Windham et al. 1991). The authors observed approximately three times the risk of spontaneous abortion with exposure to trichloroethylene. This risk increased further when women with less than a half hour of exposure to trichloroethylene each week were excluded from the analysis. However, a consistent dose-response relationship was not observed, and most of the women were exposed to a variety of solvents, not just trichloroethylene. 

Reproductive Effects. Operating room nurses exposed to trichloroethylene have been reported to have an increased incidence of miscarriages, but they were exposed to many other anesthetics as well (Corbett et al. 1974). Survey results of 1,926 women who had spontaneous abortions revealed a greater risk of abortion associated with trichloroethylene exposure (Windham et al. 1991). This study is limited by multiple chemical exposure. Humans exposed to trichloroethylene in the drinking water in certain areas of the country have not shown adverse reproductive effects (Byers et al. 1988 Freni and Bloomer 1988 Lagakos et al. 1986a). 

Reproductive Toxicity. Increased miscarriages were reported in one study of nurse-anesthetists exposed to trichloroethylene and other solvents (Corbett et al. 1974). A retrospective case-control study has should an approximate 3-fold increase in spontaneous abortion in women exposed to trichloroethylene and other solvents (Windham et al. 1991). Significant effects on sperm parameters were not observed in men occupationally exposed to trichloroethylene (Rasmussen et al. 1988). Adverse reproductive effects were not noted in humans that ingested water contaminated with trichloroethylene and other solvents (Byers et al. 

Mills J.L., Holmes L.B., Aarons J.H., et al., Moderate caffeine use and the risk of spontaneous abortion and intrauterine growth retardation. JAMA, 1993, 269,... 

Hydrogen sulfide has not been shown to cause cancer in humans, and its possible ability to cause cancer in animals has not been studied thoroughly. Hydrogen sulfide has not been classified for its ability to cause or not cause cancer. There is some evidence that exposure to hydrogen sulfide may lead to an increase in spontaneous abortions in humans. However, the studies where this effect was reported are complicated by exposures to other chemicals and a lack of information on the amount of exposure to hydrogen sulfide. 

In a recent retrospective study of spontaneous abortions in a large population of women working in the petrochemical industry in China, Xu et al. (1998) reported a significantly increased risk of spontaneous abortion with frequent exposure to petrochemicals (odds ratio of 2.7 95% Cl 1.8-3.9). When the risk associated with exposure to specific chemicals was examined, exposure to hydrogen sulfide was found to have an odds ratio of 2.3 (95% Cl = 1.2-4.4). 

There are no known studies which hydrogen sulfide levels were measured in the blood or other tissues of children. It is not clear whether hydrogen sulfide can be transferred from mother to fetus although there is limited evidence that women occupationally exposed to hydrogen sulfide have a higher rate of spontaneous abortions (Hemminki and Niemi 1982 Xu et al. 1998). 

Hemminki K, Niemi M-L. 1982. Community study of spontaneous abortions Relation to occupation and air pollution by sulfur dioxide, hydrogen sulfide, and carbon disulfide. Int Arch Occup Environ Health 51 55-63. 

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