Herpes and Pregnancy

 

The acquisition of herpes simplex virus during pregnancy

ZA Brown, S Selke, J Zeh, J Kopelman, A Maslow, RL Ashley, H Watts, S Berry, M Herd, L Corey.

ABSTRACT

Background Previous studies have suggested that the acquisition of symptomatic genital HSV infections during pregnancy is associated with prematurity, intrauterine growth retardation, congenital and perinatal HSV infection in the infant. However, no systematic study of the frequency of HSV seroconversion during pregnancy or the complications from acquiring an HSV infection during pregnancy has ever been conducted.

Methods We conducted a prospective study comparing the HSV serologic status at the first prenatal visit with that in early labor of 8,538 women of whom 7,046 (82.5%) were at risk for HSV seroconversion. The median interval between sera was 196 days (30-280).

Results - Ninety four (1.3%) women seroconverted during the antepartum period ( 2.1% when adjusted for the entire pregnancy); 60 (64%) did so asymptomatically. Among subjects who were HSV seronegative, HSV-1 seropositive or HSV-2 seropositive at the first prenatal visit, the estimated chances of seroconversion were 3.7%, 1.7% or 0% respectively. HSV seroconversion during pregnancy was not associated with discernible pregnancy morbidity, congenital or intrapartum infection of the newborn. Based on a binomial probability calculation, we are 95% confident that the chance of transmitting the infection to the newborn by a woman who acquires genital herpes during pregnancy is less than 3.2%. However, among nine women who acquired genital HSV close to the onset of labor, neonatal HSV occurred in four with one fatal infection.

Conclusions - HSV seroconversion during pregnancy is relatively common and most frequently unrecognized. When seroconversion occurs prior to the onset of labor, adverse pregnancy outcome and neonatal HSV infection are not observed. Acquisition of either HSV-1 or HSV-2 near the onset of labor is associated with significant neonatal morbidity. Serologic screening early in the third trimester to identify women at risk of acquiring HSV near term (i.e. HSV seronegative or HSV-1 seropositive) is a prevention strategy that should be considered and will be facilitated by the widespread commercial availability of type specific HSV serologic assays.

Neonatal herpes simplex virus infection in relation to asymptomatic maternal infection at the time of labor

Brown ZA, Benedetti J, Ashley R, Burchett S, Selke S, Berry S, Vontver LA, Corey L

Abstract

BACKGROUND AND METHODS. To define the risk factors associated with neonatal acquisition of herpes simplex virus (HSV) infection, we prospectively obtained HSV cultures from the cervix and external genitalia of 15,923 pregnant women in early labor who were without symptoms or signs of genital HSV infection. Follow-up of the women with positive cultures for HSV and their HSV-exposed infants included serologic tests and serial cultures for HSV. RESULTS. HSV was isolated from 56 of the women (0.35 percent), 18 of whom (35 percent) had serologic evidence of a recently acquired, subclinical first episode of genital HSV infection, and 34 of whom (65 percent) had reactivation of HSV. Neonatal HSV developed in 6 of 18 infants (33 percent) born to the women with a first episode of genital HSV, and in 1 of 34 infants (3 percent) born to the women with reactivation of HSV (P less than 0.01); neonatal HSV also occurred in three of the infants born to the 15,867 women with negative cultures. Neonatal HSV-2 occurred in 1 of 4 infants born to mothers seronegative at delivery for both HSV-1 and HSV-2, in 4 of 12 infants exposed to HSV-2 whose mothers had only HSV-1 antibodies at delivery, and in none of the infants born to 31 women who were HSV-2-seropositive. An increased risk of neonatal HSV was associated with exposure to viral shedding from the cervix and the use of fetal-scalp electrodes. CONCLUSIONS: Of the asymptomatic women who shed HSV in early labor, about a third have recently acquired genital HSV, and their infants are 10 times more likely to have neonatal HSV than those of women with asymptomatic reactivation of HSV. The presence of maternal antibodies specific to HSV-2 but not HSV-1 appears to reduce the neonatal transmission of HSV-2. Further studies are necessary to determine whether screening and prophylactic treatment are warranted for infants of HSV-2-seronegative mothers who shed HSV-1 or HSV-2 in early labor.