North American Registry of Midwives (NARM) Practice Exam

When during pregnancy is maternal varicella infection most likely to lead to congenital varicella syndrome?

1. After 20 weeks of gestation

2. In the first 20 weeks of gestation

3. After the first trimester

4. In the third trimester

The correct answer is: In the first 20 weeks of gestation

Maternal varicella infection is most likely to lead to congenital varicella syndrome when it occurs in the first 20 weeks of gestation. This timing is critical due to the development of the fetal organs and the susceptibility of the fetus to teratogenic effects during early pregnancy. Varicella infection during this period can disrupt normal fetal development, leading to a range of birth defects associated with congenital varicella syndrome, which includes skin scarring, limb hypoplasia, eye problems, and neurological abnormalities. As gestation progresses beyond the first 20 weeks, the risk of congenital varicella syndrome decreases significantly, although it may still cause serious illness in neonates if contracted around the time of delivery. Thus, the first trimester and early second trimester are key periods where the risk of severe fetal effects from maternal varicella infection is highest.