Billy A. Watson and Kerby C. Oberg
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can result in intrauterine growth retardation, micromelia (shortened limbs),
chorioretinitis, blindness, microcephaly, cerebral calcifications, mental
retardation, and hepatosplenomegaly (Chung, 2004).
Varicella Zoster Virus (VZV)
Congenital VZV syndrome describes a group of defects that include scars,
defects of muscle and bone, malformed and paralyzed limbs, small head size,
blindness, seizures, and mental retardation. During the first 20 weeks of
pregnancy, if a woman becomes infected with the varicella virus, there is a 2%
increased chance that her baby will exhibit symptoms of this syndrome
(Paryani and Arvin, 1986). This syndrome is rarely seen if the infection occurs
after 20 weeks of pregnancy (Gilbert-Barness, 2010).
Pharmaceutical Drugs
Thalidomide
To date, the most notorious drug associated with CULA is thalidomide,
which was commonly prescribed to treat nausea in pregnant women in the late
1950s and early 1960s (Bren 2001). During this period, the use of thalidomide
before 42 days of gestation led to birth defects in over 10,000 individuals from
46 different countries, with only a 50% survival rate (Vargesson, 2015).
Thalidomide impacts proximal-distal patterning, with the most common form
of limb defects reported as shortened limbs, with the arms being more
frequently affected (intersegmental defect). The range of birth defects included
phocomelia, dysmelia, amelia, bone hypoplasticity, and other congenital
defects affecting the ear, heart, and other internal organs.
Warfarin
Women with a history of thromboembolic disease or artificial heart valves
often require long-term anticoagulant therapy. There is an estimated 25% risk
for affected infants after exposure during the period from 8 to 14 weeks of
pregnancy. Warfarin inhibits the formation of carboxyglutamyl from glutamyl
residues, decreasing the ability of proteins to bind calcium (Pauli, 1988).
Calcific stippling occurs primarily in the tarsals, proximal femurs, and
paravertebral processes. Brachydactyly and small nails, with greater severity
in the upper limbs, has been present in about one-half of affected infants
(Gilbert-Barness, 2010).