It takes some time for antibodies to be produced after syphilis infection, and sufficient antibodies have been produced at 16 weeks, so if the test is still negative at this time, the possibility of syphilis can be ruled out. Syphilis is caused by syphilis spirochete infection, after infection, the body will produce the corresponding syphilis spirochete antibodies, the window period of the antibody is 4~6 weeks on average, usually 12 weeks can produce enough antibodies, so if the antibody test is negative at 16 weeks, syphilis can be excluded. Syphilis is mainly transmitted sexually, and avoiding high-risk sexual behavior (e.g. multiple sexual partners) can effectively prevent infection. To summarize, syphilis infection can be ruled out at 16 weeks, we suggest not to be too anxious, and follow the doctor’s instructions to carry out relevant examinations. Maintaining good living and hygiene habits in daily life can effectively avoid syphilis infection.