Hi Tara,
Sorry -- I'm just catching up after a busy week. Funny -- I just completed an educational slide set for doctors on the TORCH diseases and decided, at the last minute, to include Parvovirus B19, which is the virus that causes Fifth Disease (also known as erythema infectiousa or slapped cheek disease).
The lacy rash that you see with Fifth disease can sometimes be difficult to see on darker skinned complexions, so it is possible to have the disease and not see the rash, except for on the cheeks. About 65% of the population worldwide gets this disease before they're 20, but pregnant women who have not been previously exposed are at increased risk during pregnancy because of immune suppression that accompanies pregnancy (keeps your body from rejecting the baby). In general, though, if this is a standard year for parvo infection, only about 1% of all pregnant women will become infected, which is a pretty low rate. But, if this is an epidemic year (and I don't know if it is), then the risks of becoming infected are 10 times greater. Your risks are increased even more if your children really do have the disease (I don't know the actual numbers, though). Over all, in nonepidemic years, approximately 33 out of every 100,000 pregnancies will result in some problem because of parvo infection. In epidemic years, this number increases to up to 550 out of every 100,000 pregnancies. These are pretty low numbers, so you should get things checked out, but not be freaked out by them, and you should not be freaked out by the information below. It is meant to be purely informative, not scary (although it can sound that way). Just keep in mind that the chances that you and your unborn baby have been infected are small. If you have any doubts or concerns, however, get tested. It's easy, it's cheap, and it's great peace of mind.
In terms of the actual disease, these are the risks to you and your unborn child. While parvo is usually very mild in children, it can cause arthritis-like symptoms in adults, and this can last for several months or even years after the virus has cleared (it can target the synovium - the membrane that covers joints -- and cause an inflammation response). It is NOT actual arthritis, though.
Because parvo primarily acts by interrupting the generation of red blood cells and platelets, it can cause anemia and even anemic crisis in severely immune suppressed individuals (this is not a factor in pregnancy, unless you're already immune suppressed for other reasons, such as have HIV or are on immune suppressants following an organ transplant). This is a rare occurrence.
Parvo in pregnant women is associated with a higher rate of second and third trimester miscarriage and preterm delivery because it can also infect the placenta. The most significant risk from it is fetal anemia that can lead to the development of nonimmune fetal hydrops (fluid build up in the fetus). This can be mild or quite serious. The greatest risks to the fetus occur if the mother is infected before the 20th week of gestation.
So, how to decide to get tested? First: in parvo, the viral prodrome (fever, malaise, loss of appetite) occurs separately from the rash. Fever usually lasts for 3 - 7 days, then subsides and the rash shows up about 7 days later. But, the prodrome can be completely nonsymptomatic, too, as can the rash. If this was the case with your kids and you are less than 20 weeks pregnant, GET TESTED. If you have had symptoms of fever and joint aches, with or without the rash, GET TESTED. It's a simple blood test -- 2 tubes of blood, max. The doctor must test for both parvovirus B19 IgM and IgG, as the pattern of these tests will allow him to decide if you had previous immunity to parvo or if you have had a primary infection, or are susceptible to a primary infection, during pregancy.
Test results: If you are IgM-negative and IgG-negative, you have never had the disease and are at risk of getting it, so you should be closely monitored with blood tests over the next couple of weeks to see if IgM begins to rise. If you are IgM-positive and IgG-negative, or if you are IgM-positive and IgG-positive, you most likely have a primary infection (see the next paragraph). If you are IgM-negative and IgG-positive (and your exposure was very recent, like within the last 2 - 3 months), then you probably had the virus already and do not need to worry, but you might still want to mention the exposure to your obstetrician. S/he might want to order an extra ultrasound, just to be on the safe side.
If testing shows that you DO have a primary infection, then your pregnancy will be termed high risk. The doctor will need to follow the progress of your fetus closely by weekly ultrasound. He will be looking for the development of fetal hydrops. S/he should also be measuring the flow of blood in your baby's brain, which will indicate if the baby is developing anemia before signs of hydrops develop. If the baby becomes severely anemic and/or hydrops does develop and you are still early in your pregnancy, it may be recommended that you have an intrauterine blood transfusion. There are risks with this, but in general the results are very good and the likelihood is high that you will deliver a healthy baby at term. If hydrops develops close to term, the doctor may instead suggest early induction or a C-section.
There are a few papers suggesting that there can be minor nervous system developmental problems in babies exposed to parvo in the womb, especially those infected severely enough to require transfusion. There's a bit of debate about this, but if it turns out that your baby was infected, just know that it is a possibility and that you should keep a watch on his or her development through early school age (who doesn't, anyway?!). While there may be no obvious devlopmental problems early on, there is still some conjecture that they won't show up until later as learning disabilities. I always figure that it's best not to worry too much, but it is better to forewarned to be adequately forearmed!
I hope everything turns out to be just find.
R.