Consult the FAQ


Vaccines containing attenuated live viruses or bacteria are not recommended during fertility treatment and pregnancy. If you must receive such a vaccine, you should wait at least 4 weeks afterwards before trying to conceive. An example of this is the Rubella vaccine. The flu vaccine, on the other hand, is strongly recommended before starting fertility treatment, or preferably after the first trimester, if still useful.

Flu vaccine

A severe flu (influenza) can be harmful to the health of the foetus or baby. The possible consequences are premature birth, reduced birth weight, miscarriage and even death of the child shortly after birth. The Supreme Health Council recommends vaccination before the start of the flu season. The ideal period for vaccination is between mid-October and mid-November. Thus, the flu vaccine is strongly recommended before starting fertility treatment, during this period. The flu vaccine is safe even if you are breastfeeding: it does not contain live virus particles and cannot cause flu in you or your unborn baby. Only if you would be allergic to chicken protein should you not be vaccinated. Vaccination ensures that you run much less risk of falling ill, but you also pass on antibodies to your baby via the placenta. The baby is therefore doubly protected after birth: by its own antibodies and by the fact that you cannot pass on the flu, because you too are protected.
Vaccination against rubella, mumps and measles

The childhood diseases rubella, mumps and measles are contagious viral infections transmitted through coughing, sneezing and talking (saliva). In western countries, most people have experienced these diseases or have been vaccinated against them. Yet a small percentage of women are not protected for life. For pregnant women, infection with rubella is especially risky. Fortunately, it is rare, but especially in the first months of pregnancy, the consequences can be very serious: miscarriage, growth retardation, stillbirth and various abnormalities in the baby. After 16 weeks of pregnancy, the risk of abnormalities diminishes. Because of these risks for the baby, we check whether you have antibodies against rubella with a blood test prior to your MBV treatment. In Belgium, the rubella vaccine is a combination vaccine that also protects you against measles and mumps. It is administered twice, four weeks apart. After the last injection, you should wait at least 4 weeks before trying to get pregnant or starting MBV treatment. In case you would have insufficient remaining protection from the childhood vaccine, a one-time ‘booster’ is suggested with another 4-week waiting period after this injection. If you have already had such booster injection in the past 5 years, additional booster injections have proven to be of little use.


We follow the advice of the Belgian Society for Reproductive Medicine. We advise you (and your partner) to get vaccinated before the start of your fertility treatment or as soon as possible during treatment that has already started. At no point does vaccination pose an additional risk to yourself, your (future) treatment or your pregnancy. However, experiencing COVID during pregnancy does carry a risk, both for the mother and the child. Vaccination can significantly protect you and your unborn child from serious COVID-related pregnancy complications.

Whooping cough vaccination

Whooping cough is a serious and highly contagious disease of the respiratory tract and larynx. This bacterial infection is transmitted by coughing and sneezing and through the hands. Particularly in babies, serious complications can occur, partly due to the heavy coughing and persistent mucus. Vaccination or going through the disease does not offer lasting protection, especially if you were vaccinated a long time ago. You can get vaccinated against whooping cough during pregnancy. This way, you protect yourself and the foetus from the disease. The best time is between 24 and 32 weeks of pregnancy. Then there is enough production of antibodies to protect the baby in the first 2 months of its life. That is the time when he or she is vaccinated himself or herself. Vaccination of other family members is also recommended.

Hepatitis B

Hepatitis B is a viral disease that affects the liver. Transmission occurs mainly through contact with infected blood. The disease often goes unnoticed. People who have had it may remain carriers of the virus afterwards. If you want to become pregnant through fertility treatment, it is a good idea to get vaccinated against hepatitis B. This way, you avoid possible infection with the virus during your pregnancy and its possible transmission to the foetus. If you are a healthy carrier of hepatitis B, there is little risk to the foetus during pregnancy. The risk of transmission through the placenta is very small. The greatest risk is to the baby during birth, as he/she comes into contact with the virus in your bodily fluids after the waters break. To protect your baby, we will give him or her an injection of antibodies against hepatitis B a few hours after birth. Vaccination will follow at a later stage.

Hepatitis C

Like hepatitis B, hepatitis C is a viral disease that affects the liver and is transmitted mainly through contact with infected blood. 70% of infected individuals develop chronic active hepatitis, resulting in risk of liver cirrhosis and liver cancer. There is no vaccine against hepatitis C. To minimise the risk of infection during sexual contact, we recommend the use of condoms to all patients with hepatitis C. For the baby, the same applies with hepatitis C as with hepatitis B: small risk of transmission during pregnancy, greatest risk during delivery. But there is no vaccine against hepatitis C and so the baby cannot be vaccinated after birth. We will check him or her for the presence of the virus 6 months after birth.


Syphilis is a sexually transmitted infectious disease. There is no vaccine against it. During pregnancy, you can pass the bacteria to the foetus through the placenta. 30% of foetuses are not affected, but 70% have an increased risk of a range of different abnormalities. If we detect syphilis in you and/or your partner in the blood test before MBV treatment, you will first be given a course of antibiotics to fight the infection. Your MBV treatment will then be delayed.


HIV is the virus that can cause AIDS, i.e. the progressive impairment of your immune system. It is a chronic condition: if you are infected, the virus remains in your body and can be transmitted. Infection occurs through contact with body fluids containing the virus. As a result, an HIV-positive pregnant woman can pass on the virus to her baby. HIV increases the risk of miscarriage and preterm birth. For HIV-positive prospective parents, we prefer to start antiviral therapy before the start of your fertility treatment. This way, we can reduce the amount of active virus particles in the blood, which is very important to greatly reduce the risk of the baby (and others) becoming infected.