Objectives: This study aimed to reveal the knowledge level of pregnant women about prenatal diagnostic tests, Down syndrome (DS) and amniocentesis, their attitudes toward uptaking these tests, undergoing amniocentesis, and the termination of pregnancy. It also aimed to evaluate the effects of providing information, as well as a written information brochure about all the issues concerning women's knowledge and attitudes. Materials and Methods: The gynecologists provided verbal and written information on prenatal screening tests (PSTs) and invasive prenatal diagnostic tests. Data were collected using an anonymous questionnaire, which was designed by the researchers on the basis of the literature. Results: Knowledge of both DS and amniocentesis was found to be significantly higher after the education (p = 0.000 and p = 0.000, respectively). Attitudes toward amniocentesis changed significantly after the education. Conclusions: This study has shown that women had an inadequate knowledge about PSTs, DS, and amniocentesis. It has also revealed that education provided by gynecologists along with a written brochure of information tended to increase women's knowledge about PSTs.