Fortunately, Chicken Pox (Varicella Zoster) in pregnancy is unusual. In the UK approximately one in a hundred women may contract the disease while pregnant, as most will already be immune from a childhood infection. It does, however, carry extra risks for both mother and baby, especially in the early and very late stages of pregnancy.
The mother, with her altered immunity, is likely to suffer a more severe form of the illness, compared with that experienced by children or teenagers. Serious consequences are, however, very rare.
Risk of Chicken Pox to Unborn Babies
For the baby, there are extra risks, especially if the infection is in the first twenty weeks of pregnancy. These include limb defects, neurological problems, eye and skin abnormalities and occasional death of the baby. The chances of these abnormalities after proven infection before 20 weeks is approximately 1-2 per hundred cases .
Very occasionally, chicken pox can occur at the very end of pregnancy, in which case both mother and baby may catch a rather dramatic and more serious form of the infection.
It has been estimated that about seven cases of serious problems related to Varicella in pregnancy can be expected in the average year in UK. So it is very rare.
Should I vaccinate?
In the UK vaccination against Chicken Pox (Varicella) is not included with the routine childhood vaccination programme. It is, however, routinely given in USA, Germany and Australia.
It is thought not to be cost effective and surprisingly associated with an increased incidence of Shingles in elderly people.
It is recommended for health care workers who are known to be non-immune, and for people with reduced immunity from other medical or surgical conditions.
It is also advisable for women who are planning a family, and are known to be non-immune. This requires a blood test to look for Varicella antibodies.
The vaccination involves two injections, 4-8 weeks apart, and is very effective in children but only protects 75% of adults.
I’m pregnant – should I vaccinate my toddler?
Vaccination of children is not currently advised in UK, even if mother is pregnant and in the midst of an outbreak. She is 98-99% likely to be immune.
If she thinks she is not immune and in contact with possible infection, then she should have blood test to establish her status. If not immune will be offered VZIG (immunoglobulin).
Safety of the Chicken Pox vaccine
Side effects are unpredictable. About one in four will get redness or soreness over the site of the injection. A rash may occur in one in twenty, and occasionally a high temperature and flu like symptoms.
Serious reactions are approximately one in a million.
It is a live vaccine and should not be given in pregnancy, although there is no evidence of increased risk to the baby in the studies performed thus far.
Best practice is to wait three months after vaccination before conceiving.
It is, however, safe in breastfeeding mothers.
The best advice
If you are planning a baby, and unsure of your immunity, then please see your doctor and ask for a blood test.
If you’re pregnant and not sure, and in contact with an infected person, then seek urgent advice from your midwife or Obstetrician.
In certain circumstances, specific Chicken Pox Immunoglobulin therapy may be advisable which will help protect you and your baby from potential serious problems
Roger Marwood MSc FRCOG Obstetrician and Gynaecologist
Roger and his daughter Becca are the founders of A Mother Place, the home to Online Antenatal Classes. Check out their classes to find out all the things that #Nobodytells you about pregnancy, birth and what comes after!