Risk factors for Congenital Syphilis in Puerto Rico: A case-control study

The risk factors for syphilis infection in pregnant women have been largely studied. Nevertheless, few studies have determined the risk factors for the vertical transmission comparing two groups of women with syphilis, those who had an infant with Congenital Syphilis (CS) and those whose infant was born healthy. The aim of this study was to identify the risk factors for CS in Puerto Rico, and assess the role of the third trimester test that is recommended for high prevalence sites. A case-control study was performed, analyzing data from years 2000 to 2006 of the STD Surveillance System in Puerto Rico. The sample comprises 118 cases and 118 controls. Multiple logistic regression analysis revealed that crack users had 3.1 times more possibility, than non-users, of having an infant with CS; women who had two or less syphilis tests performed during pregnancy had 3.8 times more possibility of having an infant with CS than women who had at least 3 tests; and those women who did not have a syphilis test in the third trimester of pregnancy had 2.1 times more possibility of transmitting the infection to their babies than those who did get tested. We conclude the syphilis test when performed during the third trimester is a powerful tool for CS prevention in this population. This study identifies crack users as an at-risk population in which identifying the infection is not preventing the cases. Re-infection may play an important role in this subject, and should be assessed in future studies.