Objective: To investigate the incidence of congenital syphilis in newborn and secondary outcomes is to determine the other pregnancy outcomes according to adequate and inadequate treatment.

Materials and Methods: This is a retrospective cohort study involving pregnant women who undergone delivery between January 2015, and December 2021. Total 106 pregnant women with confirmed syphilis infection for each group (adequate treatment group vs. inadequate treatment group) was collected to the present study. We investigated the relationship between adequacy of penicillin treatment and adverse pregnancy outcomes.

Result: During the year 2015 to 2021, there were 28,849 pregnant women underwent delivery. The overall rate of congenital syphilis was 104 per 100,000 live births. Inadequate treatment group had significantly higher risk of congenital syphilis (28.3% VS 0%, p<0.001), low birth weight (27.4% VS 15.1%, p=0.031), birth asphyxia (11.3% VS 0%, p<0.001) and late preterm delivery (18.9% VS 9.4%, p=0.017), still birth (7.5% VS 0%, p=0.007) than adequate group. The syphilitic mother who received adequate treatment before 28 weeks' gestation had significantly lower risk of congenital syphilis newborn, preterm labor, and birth asphyxia.

Conclusion: The trend of congenital syphilis increases with time that passes in untreated or inadequate treatment syphilitic mother. Adequate penicillin treatment before 28 weeks’ gestations can prevent congenital syphilis, preterm delivery, birth asphyxia, and still birth. Prevention and control strategy for syphilis before pregnancy and antenatal care follow up protocol during pregnancy is very important.

Jiraporn Luengmettakul, MD, is a specialist in maternal–fetal medicine working in the Maternal Fetal Medicine Unit, Department of Obstetrics and Gynecology, at Charoenkrung Pracharak Hospital under the Division of Medical Services, Bangkok Metropolitan Administration, Thailand.