Pityriasis rosea and other infectious eruptions during pregnancy: Possible life-threatening health conditions for the fetus.

Any infectious illness presenting with an eruption in a pregnant patient may be associated with an increased risk of fetal loss. The viruses that can infect the placenta during maternal infection and can be transmitted to the fetus and cause congenital disease include the rubella virus, the measles virus, the varicella zoster virus, parvovirus B19, human cytomegalovirus, arboviruses, and hepatitis E virus type 1. In addition, some bacteria responsible for exanthematous diseases, like Treponema pallidum, can be transmitted during pregnancy from the mother to the fetus and cause fetal loss. All these infectious agents can cause typical and/or atypical exanthems whose etiologic diagnosis is sometimes difficult but important to determine, especially in pregnant women because of the potential risk to the fetus. In the last 20 years, we have extensively studied pityriasis rosea from the clinical and laboratory perspectives, demonstrating the pathogenic role of human herpesvirus (HHV)-6 and -7. We synthesize the available evidence that PR may be associated with active HHV-6/7 infection and therefore with complications during pregnancy and fetal loss. We have also summarized the emerging infectious illnesses of dermatologic interest that may represent life-threatening health conditions for the fetus: measles, rubella, arbovirus infection, and syphilis.