Sexually transmitted infections (STIs) are a major global public health problem. More than 1 million STIs occur every day. The majority of STIs occur without symptoms. STIs are relevant in different aspects of pregnancy. Some of them can cause infertility, others may affect the normal course of pregnancy or the development of the fetus, while others can be transmitted to the newborn and cause chronic illness. All pregnant women should be tested for STIs in the first trimester of pregnancy. If the patient is HIV positive, some tests should be performed at the preconception visit. If the pregnant patient is at high risk for acquisition of STIs, the tests should be repeated in the third trimester. Approximately 300 million women are infected with human papillomavirus (HPV) and this number is likely similar in men. When the patient attends the first pregnancy visit, it is important to pay attention to whether she has undergone a correct cervical cancer screening. Some STIs have a cure or a vaccine, but only by efforts involving primary prevention, early detection, and efficacious treatments will we achieve efficient control of them.