We thank Drs Straface et al for their interest in our study. The placenta does play a pivotal role as an immunological barrier against congenital cytomegalovirus (cCMV) but also as a reservoir in which cytomegalovirus replicates. Invasive access to the placenta would only be focal and therefore histological samples unlikely to be consistently helpful in the absence of an available biomarkers of prognosis.

Imaging is limited to date to ultrasound characterization of placentitis with placentomegaly, but functional magnetic resonance imaging is a promising approach. Magnetic resonance imaging is already a useful adjunct to ultrasound and fetal laboratory findings to anticipate postnatal outcome.

Guidelines on prenatal management are expectedly prudent. However, cCMV remains the main cause of congenital neurological impairment. The anxiety raised by the diagnosis of fetal infection is unlikely to be alleviated by inaction, and the alternative of otherwise unfounded early termination is not appropriate.

Extensive and invasive assessment of infected fetuses is likely to yield early and reliable reassurance but also to define cases susceptible to benefit from prenatal treatment. This is achievable within fetal medicine units. Placebo-controlled trials are desirable. However, an unacceptable likelihood of a poor outcome in the placebo group is likely to collide with the free will of pregnant women. In other areas of medicine such as postnatal symptomatic infectious diseases, placebo is justifiably not an option. Further studies should be encouraged under strict control and fully informed consent from pregnant women.