Charles Grose, M.D.
University of Iowa Hospitals and Clinics
First Published: Spring 2002
Last Revised: August 2003
Peer Review Status: Internally Peer Reviewed
Chickenpox is a feared illness in the pregnant woman, because of at least two complications. The first is the congenital defects syndrome in the fetus. The second is life-threatening varicella pneumonitis in the pregnant woman. Several recent telephone consultations have raised concerns about the management of chickenpox during pregnancy. I am aware of the chickenpox-related death of one pregnant woman in the late 1990s in northeastern Iowa. This issue has even led to medical legal consequences in Iowa, so I thought that it would be useful to review all possible treatment regimens.
Chickenpox in the Pregnant Woman
All pregnant women who contract chickenpox should be treated immediately with an antiviral agent. The traditional treatment is acyclovir tablets at the shingles dosage of 800 mg five times daily; the duration of treatment is 5-7 days. The main side effect is gastric indigestion, so acyclovir tablets should be taken with food. Because it is difficult to take five very large tablets per day, I personally recommend the second-generation drug (famciclovir) at a dosage of 500 mg TID. Usually five days of famciclovir are sufficient to treat chickenpox in an adult. If the pregnant woman develops shortness of breath, a chest film should be obtained. If there is even minimal evidence of pneumonitis, I recommend that the pregnant woman be admitted to a hospital with an intensive care unit for treatment with intravenous acyclovir and monitoring of blood gases.
Chickenpox in a Child of a Varicella-Zoster Virus (VZV) Susceptible Pregnant Woman
Management of the Pregnant Woman
Chickenpox is of special concern when the pregnant woman is less than 24 weeks' gestation. The reason is the fetal varicella defects syndrome, consisting of cutaneous scarring, cataracts, and limb defects. This syndrome only occurs when a pregnant woman develops chickenpox before 24 weeks of gestation. After 24 weeks, the fetus is not at risk when the pregnant woman has chickenpox. Nevertheless, the pregnant woman is at risk throughout gestation for varicella pneumonitis if she contracts chickenpox.
To avoid chickenpox in the pregnant woman, I recommend that prophylaxis be given to the pregnant woman as soon as chickenpox is diagnosed in a child living in the same household. Previously, there has been a general recommendation that pregnant women be given varicella-zoster immune globulin (VZIG) at a dosage of five vials. Each vial contains about 1.2 ml of fluid, so the total volume is about 6 ml, a large amount to give any adult by intramuscular injection at one time. VZIG must be administered within 72-96 hours after chickenpox exposure to be effective. The dosage of VZIG is an extrapolation of the dosage for a child: one vial for every 20 pounds, up to five vials for a 100-pound child. There were never any VZIG efficacy studies carried out in adults in the USA. It is reasonable to assume that VZIG will be efficacious in adults who weight 100 to 120 pounds. However, for a substantially heavier pregnant woman, it seems less likely that a VZIG dosage calculated for a 100-pound person will be efficacious.
In my experience, the VZIG recommendation is difficult to follow for several reasons:
For all the above reasons, I suggest the following alternative approach. As soon as a pregnant woman notifies her physician that she has been exposed to chickenpox, verify that she is truly VZV susceptible. Send a blood sample to a testing laboratory for VZV antibody titer. If confirmed to be susceptible, begin treatment of the pregnant woman with prophylactic acyclovir at a dosage of 800 mg TID for seven days. The acyclovir should be initiated by between 5-7 days after exposure (the onset of chickenpox in her child) and continued for 10 days.
If the pregnant woman develops chickenpox in spite of the acyclovir prophylaxis regimen, switch immediately to famciclovir at a dosage of 500 mg TID for another five days. Note that the Varivax vaccine should never be administered to a pregnant woman.
Treatment of the Other Children
If the family has other children, the following recommendations are made. If the other children have had Varivax, no further therapy is indicated. If the other children have not had Varivax or chickenpox, administer Varivax within the next 24 hours. Varivax, given quickly after exposure, will prevent chickenpox in the VZV-susceptible children and thereby limit the spread of chickenpox within the household.
For a child under the age of one year, Varivax should not be administered. It is recommended that the infant be treated with oral acyclovir suspension (20 mg / kg per dose QID) if the infant develops chickenpox.
Treatment of the Father in the Same Household If a father of a VZV-susceptible pregnant woman is also VZV-susceptible, it is recommended that the father also be treated with a prophylactic regimen of acyclovir (800 mg TID for 10 days). If the father develops chickenpox in spite of prophylaxis, it is recommended that he be treated with famciclovir, 500 mg TID, for five days.
Management of the Family after Delivery of the Newborn
If the mother who was exposed and given prophylaxis never develops chickenpox, the VZV antibody titer can be re-tested after delivery to determine if she had subclinical varicella infection. If the titer is still negative, the mother should be administered two sequential doses of Varivax, one month apart.
A similar strategy is recommended for the father.
Chickenpox in the Postnatal Infant
When a pregnant woman contracts chickenpox after 38 weeks of gestation, but before parturition, the newborn can occasionally develop chickenpox following intrauterine transmission. One vial of VZIG should be administered soon after delivery. Newborns with chickenpox during the first two weeks of life are at high risk for morbidity and mortality. In most cases, admission for treatment with intravenous acyclovir is strongly recommended. Consultation with a Pediatric Infectious Disease Specialist is also recommended.
Exposure to Chickenpox in a Newborn in the First Month of Life
Occasionally, a newborn is exposed to chickenpox from an infected sibling. If the mother is VZV immune, the newborn will have received transplacental anti-VZV antibody and may have mild disease. Nevertheless, it is recommended that every infant of less than one month of age who contracts chickenpox from a postnatal exposure be treated with acyclovir suspension at a dosage of 20 mg / kg QID for seven days. The suspension contains 200 mg / 5 ml.
Zoster in a Pregnant Woman or in Household
Shingles or herpes zoster in a pregnant woman has never been associated with the development of the congenital defects syndrome in the fetus. Nevertheless, in order to prevent other consequences such as post herpetic neuralgia, it is recommended that active shingles in the pregnant woman be treated immediately with famciclovir at a dosage of 500 mg TID for at least five days.
There is one other very rare situation. Remember that shingles is contagious, although probably for not more than two days at the onset. Therefore, if a VZV-susceptible pregnant woman lives in a household where another member develops shingles, the pregnant woman has been exposed to VZV infection. In this situation, follow the same protocol as for VZV exposure to the pregnant woman from a child with chickenpox.
See related Provider Textbooks about Obstetrics and Gynecology.
See related Provider Topics Chickenpox, Child and Teen Health, Food, Nutrition and Metabolism, Infections, Obstetrics, Obstetrics and Gynecology, Pregnancy, Pregnancy and Reproduction, Prenatal Care or Women's Health.
See related Patient Textbooks about Obstetrics and Gynecology.
See related Patient Topics Chickenpox, Child and Teen Health, Food, Nutrition and Metabolism, Infections, Obstetrics, Obstetrics and Gynecology, Pregnancy, Pregnancy and Reproduction, Prenatal Care or Women's Health.
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