Reactivation of Polyomavirus hominis 1 (BKV) during pregnancy and the risk of mother-to-child transmission.

Background: Pregnancy is associated with down-regulation of immune responses of the mother. This might lead to reactivation and vertical transmission of latent viral infections such as BK virus (BKV).

Objectives: To determine the presence of BKV in the urine of pregnant women and in cord blood at delivery.