Women who are thinking about getting pregnant or who have recently become pregnant should find out whether they are immune to chickenpox.
The Society of Obstetricians and Gynaecologists of Canada says pregnant women or women planning to conceive need to know their immunity status because the chickenpox virus poses a high risk both to them and to their fetus.
Chickenpox is caused by the varicella zoster virus, and can be serious -- even fatal -- to pregnant women, especially when contracted in the third trimester.
Most women are safe; over 90 per cent of Canadians are immune to chickenpox, either because they've been infected earlier in life with chickenpox or because they've had the vaccination against it.
But women who have not been exposed to the virus are at risk. Even being in the same room for an hour or more with someone with chickenpox can put a pregnant woman at risk.
About 5 to 10 per cent of women who contract chickenpox while pregnant will develop a potentially fatal lung condition called pneumonitis.
Their babies are also at risk, particularly during the first half of the pregnancy. The virus can lead to birth defects such as musculoskeletal or brain abnormalities.
Babies exposed to the virus up to five days before or during delivery are also at risk of developing neonatal varicella. Although it is rare, the condition can affect the brain and central nervous system and lead to death.
Women who don't think they have immunity to chickenpox should let their doctor know as soon as possible, the guidelines advise.
The guidelines also advise that pregnant patients who doesn't know their immunity status but who may have recently been exposed to someone with chickenpox should be offered varicella zoster immunoglobulin, which can help prevent infection.
A vaccine against chickenpox has been available in Canada since 1998. Most provinces include the vaccine as part of their publicly funded immunization programs.
The vaccine is not recommended during pregnancy because it is made from a live, though weakened, virus. As well, women should wait at least four weeks after getting the vaccine before trying to conceive, the guidelines advise.
