Congenital malformations incidence

The incidence of congenital malformations such as cryptorchidism (undescended testes) and hypospadias (malformation of the penis) may have increased, but... 

Experimentally produced zinc deficiency in toad (Bufo arenarum) embryos resulted in adults with abnormal ovarian development, altered meiotic and ovulation processes, and embryos with a high incidence of congenital malformations (Herkovits et al. 1989). 

The incidence of congenital malformation is approximately 3% to 5%, and it is estimated that 1% of all birth defects are caused by medication exposure. Adverse fetal drug effects depend on dosage, route of administration, concomitant exposure to other agents, and stage of pregnancy when the exposure occurred. 

The study did not provide data on the heptachlor level in the milk of nonexposed women. Therefore, the data are inadequate to establish a relationship between exposure to heptachlor and human developmental toxicity. Milk fat levels of heptachlor measured in Hawaii during this time ranged from 0.12 to 5.00 ppm (ERA S "worst case" estimates on record range from 0.10 to 1.20 ppm). No increase in fetal or neonatal deaths or incidence of low birth weight infants were found in this study cohort. Of the 23 categories of major congenital malformations evaluated, 22 were found to be decreased in the study population when compared with comparison cohorts from the other... 

Formal human studies are limited and based on naturalistic exposure with an attempt to have a control group matched as closely as possible. However, there are inevitably differences in such groups, the most obvious and perhaps most important being the reason why one group is on a medication while the other is not. In other words, the illness that led to treatment with the medication (in this case a mood disorder) may itself be a risk factor for lower fetal viability, increased incidence of perinatal complications, or congenital malformations including neurodevelopmental problems, as well as major structural anomalies (e.g., cleft palate, spina bifida). 

The normal incidences are taken to be those of the UNSCEAR column in Table 7-5. The mutation component is taken to be 0.1 for congenital malformations and other multifactorial conditions and 1 for the other categories. The mean persistence times are taken as 4 for dominant and X-linked, 100 for recessives, 1.25 for chromosomal, and 10 for congenital anomalies and multifactorial traits. The normal frequency is 10.5 per 100 live births. The contribution from dominant, X-linked, and cytogenetic disorders is hatched. Because recessive diseases make almost no contribution, the white areas are mainly congenital malformations and other multifactorial conditions. 

In the National Transplantation Pregnancy Registry, there was no evidence of an increased incidence of congenital malformations among 25 infants born after 27 pregnancies in tacrohmus-treated hver transplant patients (99). 

Female dentists and dental assistants exposed to metallic mercury vapors had increased reproductive failures (spontaneous abortions, stillbirths, and congenital malformations) and irregular, painful, or hemorrhagic menstrual disorders (Sikorski et al. 1987). Correlations were observed between the incidence of these effects and hair mercury levels. 

The vast majority of children are bom healthy. The overall incidence of congenital malformations is approximately 3% to 5% Although many people assume that medications play a large role in causing birth defects, it is estimated that medication exposure accounts for less than 1% of all birth defects. Genetic causes are responsible for 15% to 25%, other environmental issues (e.g., maternal conditions, infection, and mechanical deformations) account for 10%, and the remaining 65% to 75% of congenital malformations result from unknown causes. ... 

In some studies, effects in females included an increased incidence of spontaneous abortion at levels as low as about 2 ppm (6-7 mg/m3) (Heinrichs 1983 Wang and Zhao 1987). Other epidemiological studies have not corroborated these reports, however. In a community study of spontaneous abortion, occupation, and air pollution, the study authors found no relationship between carbon disulfide concentrations and miscarriage rates (Hemminki and Niemi 1982). Another study reported that women exposed to 0.5-4.7 ppm (1.7-14.8 mg/m3) had significantly more menstrual disorders than nonexposed women however, there was no increase in the rate of spontaneous abortion, stillbirth, premature delivery, or congenital malformation (Zhou et al. 1988). Increased rates of menstrual disorders and toxemia of... 

Chashschin et al. (1994) reported increased incidences of congenital defects and spontaneous or threatened abortion in 758 Russian women who were employed in a nickel hydrometallurgical refining plant. They found congenital malformations in 17% of live-born infants of the nickel-... 

Misunifications in the top bilaterian, Homo. The incidence of the congenital malformation CL/P, with or without cleft palate, is high at 1 in 700 live birth world-wide. In the human embryo the formation of the upper lip is accomplished between days 24 to 37. The stomodeum (primitive mouth) is surrounded by derivatives of the branchial arch 1, prominences frontonasal superiorly, maxillary bilaterally and mandibular inferiorly and bilaterally. The fix>ntonasal prominence becomes the medial nasal process and the nose. The maxillary and the mandibular prominences fuse in the midline the upper lip is formed by this union. It is questioned if the medial nasal process contributes to the fosion in the upper lip. The processes formatted bilaterally around the stomodeum will not unite and fuse in the CL/P syndrome. 

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