The main effect of parvovirus infection is fetal anaemia. The most common presentation of fetal infections is by non-immune hydrops, diagnosed on an ultrasound scan. Hydrops can develop up to 12 weeks, and possibly 18 weeks, after maternal infection. Therefore, detailed ultrasound examination for signs of fetal hydrops should be undertaken for at least 12 weeks from the date of the exposure, or proven maternal infection.
