Objective: To study seroprevalence and incidence and fetal transmission of varicella zoster virus (VZV), cytomegalovirus (CMV), herpes simplex virus (HSV) types 1 and 2 and parvovirus B19 infections during pregnancy and to evaluate the reliability of maternal past history of VZV, HSV and parvovirus infections.

Design: Prospective study of parturient women.

Setting: South-Western Finland.

Participants: Five hundred and fifty-eight parturient women.

Methods: IgG and IgM antibodies against VZV, CMV, HSV-1 and -2, and parvovirus B19 were measured from maternal serum in the first trimester and at delivery and from cord serum, mother's own information of her past infections was compared with her serological status.

Main outcome measures: Seroprevalence, seroconversions and fetal transmission of VZV, CMV, HSV and parvovirus B19, reliability of maternal history of VZV, HSV and parvovirus B19.

Results: Seroprevalences were 96.2% for VZV, 56.3% for CMV, 54.3% for HSV, 46.8% for HSV-1, 9.3% for HSV-2 and 58.6% for parvovirus B19. Parity was associated with CMV seropositivity, maternal age differed only between HSV-2 seropositive and seronegative women, while area of residence (urban or rural) had no effect. Six seroconversions were observed: two VZV, one CMV and three parvovirus infections. No cases of primary HSV infections occurred. Fetal transmission was observed in two cases of parvovirus infection. No infants with anti-CMV IgM antibodies were born to CMV immunised women. False positive history of chickenpox was given only by 1.5% of the women, history of herpes infections was less reliable, and history of parvovirus infection was unreliable.

Conclusions: Seroprevalence and the risk of viral infections during pregnancy cannot be extrapolated from one pregnant population to another.