Previous studies reported controversial results regarding the possible association of recurrent genital herpes during pregnancy with a higher risk of preterm birth/low birth weight in newborns. Thus, birth outcomes of mothers with prospective and medically recorded symptomatic recurrent genital herpes confirmed by serological examination and of mothers without genital herpes were compared in the population-based large data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities. Our results showed that of 38,151 newborn infants, 86 (0.23%) had mothers with symptomatic recurrent genital herpes confirmed by serological examination during pregnancy. The rate of preterm births (14.0% vs. 9.2%) was higher in babies born to mothers with symptomatic recurrent genital herpes (OR with 95% CI: 1.7, 1.0–3.1) and this increase showed a trimester dependence with the highest rate in the third trimester (23.5%; OR with 95% CI: 2.6, 1.5–4.5). In conclusion, clinically diagnosed recurrent genital herpes during the third trimester of pregnancy associated with high risk for preterm birth.