Vaccine
Talk

Certain vaccines are safe and recommended for women before, during, and after pregnancy to help keep them and their babies healthy. The antibodies mothers develop in response to these vaccines not only protect them, but also cross the placenta and help protect their babies from serious diseases early in life. Vaccinating during pregnancy also helps protect a mother from getting a serious disease and then giving it to her newborn.

During pregnancy, your immune system (the body's natural defence) is weakened to protect the pregnancy. This can mean you're less able to fight off infections such as flu.

Pregnant women are more likely to get flu complications (such as pneumonia) than women who are not pregnant, and are more likely to be admitted to hospital. CDC recommends getting vaccinated by the end of October. Getting the flu vaccine during pregnancy is one of the best ways to protect yourself and your baby for several months after birth from flu-related complications.

Pregnant women are also encouraged to get the Tdap vaccine at any time during pregnancy, but optimally between 27 and 36 weeks of each pregnancy, to protect yourself and your baby from pertussis, also known as whooping cough. This vaccine is recommended during every pregnancy, regardless of how long it has been since you previously received the Tdap vaccine.

If you did not get a Tdap vaccine during your pregnancy and have never gotten it, CDC recommends that you get the vaccine immediately after giving birth.

Respiratory syncytial virus (RSV) is a common virus that causes coughs and colds. RSV usually gets better by itself, but it can be serious for babies.

RSV can cause serious lung infections (including pneumonia and bronchiolitis), which can make it difficult for babies to breathe and feed. These illnesses may need to be treated in hospital.

When you have the RSV vaccine in pregnancy, the protection from the vaccine is passed to your baby. This means your baby is less likely to get severe RSV for the first 6 months after they're born.

You should be offered the RSV vaccine around the time of your 28-week antenatal appointment. Getting vaccinated as soon as possible from 28 weeks will provide the best protection for your baby. But it can be given later if needed, including up until you go into labour.

If a vaccine uses a live version of the virus, such as the MMR vaccine, you'll usually be advised to wait until after your baby is born before you get vaccinated. Live vaccines include:

• BCG (vaccination against tuberculosis)
• MMR (measles, mumps and rubella)
• oral typhoid
• yellow fever

Wild-type rubella infection might result in spontaneous abortion, stillbirth, and, of most concern, congenital rubella syndrome (CRS), with its hallmark characteristics of sensorineural deafness, congenital heart defects, microcephaly, learning difficulties, and eye and bone defects. Measles infection in pregnancy might result in substantial maternal morbidity, an increased abortion rate, prematurity, stillbirth, and possibly congenital malformations. The data for mumps infection are not consistent, with some studies showing a possible increased rate of spontaneous abortion.

There have been no reports of congenital malformations attributable to the MMR vaccine virus. The Centers for Disease Control and Prevention (CDC) estimated the theoretical risk to the fetus of CRS following vaccination with the rubella vaccine to be 0% to 1.6%.

In 1971, the CDC established the Vaccine in Pregnancy registry of women who had received rubella vaccines within 3 months before or after conception. By 1989 there were data on 1221 inadvertently vaccinated pregnant women. There was no evidence of an increase in fetal abnormalities or cases of CRS in the enrolled women or the 321 rubella-susceptible women; therefore, enrolment in the registry ended.

Varicella virus infection during pregnancy is associated with a risk of congenital varicella syndrome, characterized by low birth weight, skin scarring, ophthalmologic defects, limb hypoplasia of bone and muscle, neuropathic bladder, and gastrointestinal and neurologic abnormalities.

There are no reports of congenital varicella syndrome after exposure to varicella vaccine during pregnancy. A registry was established by the manufacturer in collaboration with the CDC to monitor maternal and fetal outcomes of women who were inadvertently immunized with varicella vaccine in the 3 months before conception or at any time during pregnancy. Among the 737 women with pregnancy outcomes available, there were no patterns of defects and no infants were born with features consistent with congenital varicella syndrome among any of the women enrolled or among the seronegative women.

Exposure to either live or inactive vaccines during pregnancy has not been associated with an increased risk of adverse pregnancy outcomes, and no child to date has been born with CRS or varicella syndrome following rubella or varicella vaccination of the mother anytime during pregnancy. However, despite this evidence-based information, these vaccines remain contraindicated during pregnancy, and the Public Health Agency of Canada and the ACIP continue to recommend that women avoid becoming pregnant for approximately 1 month following vaccination. They do state that if pregnant women are exposed to these vaccines or if pregnancy occurs soon after vaccination, the women should be counseled regarding the theoretical risks to the fetus and vaccination should not be a reason to consider termination of pregnancy.