Risk of Congenital Syphilis (CS) Following Treatment of Maternal Syphilis: Results of a CS Control Program in China

Background: Early screening for syphilis among pregnant women and the effective treatment of maternal syphilis is fundamental to prevent congenital syphilis (CS). Methods: We obtained data from the Shenzhen Program for Prevention of CS (SPPCS) and estimated incidence rates of CS among infants born to syphilis-seropositive women treated with different regimens or untreated for maternal syphilis. Results: A total of 4746 matched cases of syphilis-seropositive mothers and their infants were included for analyses, and 162 infants were diagnosed with CS, providing an overall incidence of 3.41% (95% confidence interval [CI], 2.91%-3.98%). Among infants born to syphilis-seropositive women who had syphilis and were adequately treated before pregnancy, the incidence was 0.22% (95% CI, .05%-.66%). There were 159 cases of CS occurring in 3519 infants born to women who were syphilis-seropositive during their pregnancies, for an incidence of 4.52% (95% CI, 3.84%-5.28%). The incidence of CS was 1.82%-11.90% lower among infants born to the women treated with early benzathine penicillin G (BPG) compared with those treated with late BPG (adjusted odds ratio [aOR], 8.06 [95% CI, 2.93-22.21]; P < .001), other antibiotics (aOR, 7.71 [95% CI, .86-69.28]; P = .068), or those untreated (aOR, 68.28 [95% CI, 29.64-157.28]; P < .001). The incidence rates were 0.22% (95% CI, .06%-.80%) and 0.59% (95% CI, .35%-1.02%) in infants born to women treated with 2 courses and 1 course of BPG, respectively, corresponding to a risk difference of 0.37% (aOR, 1.74; 95% CI, .37-8.26). Conclusions: Treatment of syphilis-seropositive pregnant women with 1 course of intramuscular BPG before 28 gestational weeks is critical for prevention of CS.