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08.08.04 (4 years ago)
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Viral infections in pregnancy are major causes of morbidity and mortality for both mother and fetus. Infections can occur in the neonate transplacentally, perinatally (from vaginal secretions or blood), or postnatally (from breast milk or other sources).
Traditionally, the only viral infections of concern during pregnancy were those caused by rubella virus, cytomegalovirus (CMV), and herpes simplex virus (HSV). Other viruses now known to cause congenital infections include parvovirus B19 (B19V), varicella-zoster virus (VZV), coxsackieviruses, measles virus, enteroviruses, adenovirus, and human immunodeficiency virus (HIV).
Worldwide, congenital HIV infection is now a major cause of infant and childhood morbidity and mortality, with an estimated 4 million deaths occurring since the start of the pandemic. The breadth and depth of this problem is beyond the scope of this article, which focuses on other viruses of concern.
Discussion
Congenital rubella syndrome in the first 16 weeks of pregnancy causes intrauterine growth restriction (sometimes termed intrauterine growth retardation), intracranial calcifications, microcephaly, cataracts, sensorineural defects, cardiac defects, hepatosplenomegaly, osteitis, or miscarriage. If rubella virus infection occurs in the first 12 weeks of pregnancy, up to 90% of patients have some manifestations of the congenital rubella syndrome. For infection at 12-16 weeks, the risk is approximately 20% (Miller, 1982).
Congenital CMV infection is the most common congenital viral infection and results in intrauterine growth restriction, sensorineural hearing loss, intracranial calcifications, microcephaly, hydrocephalus, hepatosplenomegaly, delayed psychomotor development, and optic atrophy. Approximately 30% of maternal infections during pregnancy result in congenital infection. Most infections (90%) cause no symptoms, but 10% cause microcephaly, thrombocytopenia, hepatosplenomegaly, and/or intrauterine growth restriction. Seven percent of asymptomatic neonates develop sensorineural hearing loss or developmental delays during the first 2 years of life (Boppana, 2001; Trincado, 2001; Gaytant, 2002; Lipitz, 2002; Pass, 2002).
HSV-1 and HSV-2 cause neonatal herpes. Ninety percent of infections are perinatally transmitted as a result of acquisition of the virus in the birth canal. HSV has a 70% risk of dissemination and is associated with skin lesions, encephalitis, and neurological disability. Approximately 10% of infections are congenital, usually a consequence of the mother acquiring HSV during pregnancy. This route of infection is associated with intrauterine growth restriction, preterm labor, and miscarriage (Brown, 1997; Covey, 2000).
B19V, the causative agent of erythema infectiosum (fifth disease), has been shown to cause fetal anemia, hydrops fetalis, myocarditis, and intrauterine fetal death. Infection occurs most commonly in the winter and spring. Various studies have estimated that 3-14% of intrauterine fetal deaths occur in the setting of B19V infection. Second-trimester infections have been studied most frequently because infection in this trimester carries a 1-3% risk of hydrops; however, infection in any trimester may result in intrauterine fetal death. Most of the deaths in the third trimester have not been associated with hydrops (Skjoldebrand-Sparre, 2000; Tolfvenstam, 2001; Norbeck, 2002; Nyman, 2002).
VZV is a common virus that carries risk for both mother and fetus during pregnancy. If the mother develops primary varicella during pregnancy, especially in the third trimester, she is at risk for varicella pneumonia. Subclinical infection also may play a role in neonatal morbidity (Mustonen, 2001). The mortality rate was 36%; the rate is now closer to 10%. Congenital varicella syndrome (CVS) results in spontaneous abortion, chorioretinitis, cataracts, limb atrophy, cerebral cortical atrophy, and neurolo .....
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