Important: This is intended as general information only. It may not apply to your specific situation. It is not a substitute for medical advice. If you have a question or concern, please raise it with me at your next appointment or contact me sooner if it's urgent.
Parvovirus B19 in pregnancy
Parvovirus B19 is one of the many viruses that young kids pick up and is also known as ‘slapped cheek’ or ‘fifth disease’. Children with parvo often develop a fever and one bright red cheek and may have swollen joints. Adults who get infected often have no symptoms at all.
This is not the same as the type of parvovirus that puppies get. It is not possible to catch parvo from an infected puppy. Unfortunately, while you can get your dog immunized, there is no vaccine for parvovirus in humans.
I will do a blood test at your first visit to see if you already have antibodies to parvovirus – about 60% of adults do. If you already have antibodies, it tells us that you have been infected with parvo in the past (whether you remember it or not) and you will not become infected again, no matter how many times you are exposed. If this is the case, you don’t need to worry about parvovirus infection in pregnancy.
If you are not immune, I will of course discuss this with you in more detail.
If you are not immune and have been exposed to parvovirus, the first thing we need to do is determine whether or not you have become infected with the virus. As you may not get any symptoms, we do this by performing two blood tests, 14 days apart, to see if your body has mounted an immune response.
If we determine that you have been infected, there is a 20% (or one in five) chance that the infection will spread across the placenta to your baby. Most babies that are infected in utero are fine – the infection runs its course without affecting the baby. A small number of babies develop a temporary problem in which their bone marrow stops producing red blood cells. This eventually fixes itself but your baby may become anaemic in the meantime. To see whether this is happening, we do regular ultrasounds to measure the blood flow in the baby’s brain which tells us whether or not the baby is anaemic. If your baby does become dangerously anaemic, we can (amazingly enough) give him or her a blood transfusion while still in the uterus. It’s a very small minority of babies that require this treatment and, for those that do, it’s a temporary measure until their bone marrow recovers (which it always does).
This sounds like a pretty stressful situation (and it is) but remember that only a tiny proportion of babies actually need treatment and that treatment is available. For this reason, if you discover that you have been exposed to parvovirus, you should let me know so that we can start the monitoring process.