Chicken pox, also known as Varicella, is a childhood viral illness that can affect your fetus if you are not immune and you contract it during your pregnancy. Fortunately, most women are immune because they had it as a child. However, in the US, about 1 in 2000 pregnant women will contract it every year.
Chicken pox will often start with flu-like symptoms that include a sore throat, fatigue, sore muscles, and a fever. Very itchy blister-like spots, seen mostly on your abdomen and head, will follow. About 15% of pregnant women can get a severe pneumonia, which can cause preterm labor.
It takes 10 to 21 days after exposure before the rash appears. A person is contagious 2 days prior to the rash appearance and remains contagious until the rash has crusted over, which is usually 5 days or so after it first appeared.
About 90% of women in the US are immune due to vaccinations or from having contracted it during childhood. If you are immune, you cannot get it again and so you are safe. If you are not sure that you are immune, you can contact your health care provider who can do a simple blood test to verify if you are immune or not.
Prior to getting pregnant, do get vaccinated if you are found to not be immune. If you have recently been vaccinated, you should wait one month before trying to conceive. Vaccination is not recommended if you are pregnant.
If you are pregnant and not immune, be aware that the virus is extremely contagious. Also be aware that the virus is spread mostly from coughing and sneezing, but it can also be transmitted through direct contact with the rash. Try to stay away from people with shingles, which is a form of reactivated chickenpox, since shingles can spread the chicken pox virus to you (although at a much lower transmission rate). Finally, realize that you can also catch chicken pox from a recently vaccinated child, though this is extremely rare. Due to its rareness, it is still recommended that you get your children vaccinated if it is in their vaccination schedule. Avoid any blisters that appear near the vaccination spot.
If you contract the disease while pregnant, birth defects can occur. They are very rare if you are in the second half of your pregnancy (over 20 weeks pregnant). However, if you are in the first half of your pregnancy, the risk for birth defects is about 2%. The birth defects are known as Congenital Varicella Syndrome or CVS. They cause a combination of skin scars, brain and eye damage, arm and leg deformities, and other neurological problems. An ultrasound can pick up some but not all of these defects.
Near the time of birth, if you get exposed 5 days or less prior to birth or 2 days or less after the birth, your baby will not have received significant protection from your immune system and will, in up to 50% of cases, develop a serious neonatal form of chicken pox, which can be fatal. Treatment with VariZIG, an Immune globulin, and antiviral drugs are very helpful. VariZIG needs to be given within 96 hours of exposure.
If you think you have contracted chicken pox, contact your health care provider immediately. If your immune status is unclear, a blood test will be done to see if you are a candidate for VariZIG and antiviral medications. A perinatologist, a high-risk pregnancy specialist, will then follow your pregnancy closely.