Abortion dates back to the first time a person decided that they did not want a child, and therefore decided to terminate its life using any one of several methods. Prior answers can give you a good timeline on this fact, but here in the United States, one of the most infamous ways abortions took place was by way of wire coat hanger in the 1960s and before. To avoid being edited, I will not go into gross detail about how the act was performed, but needless to say, it was very damaging to the mother, and obviously fatal to the fetus.
Modern abortion clinics go about the process in a more sterile way, but the end result remains the same. I agree with the previous poster about the fact that you will want to view pages from both the left and right on this issue to gain a broad perspective. Abortion is perhaps one of the most controversial "hot button" issues dividing this country.
Abortion is not a contemporary issue. It is impossible to discuss the first woman to undergo this procedure. Women as far back as the 5th century have undergone methods to terminate pregnancies. Since that time, the methods of termination have varied. Early physicians were still very ignorant to anatomy, many of the first abortion methods were painful as well as primitive. Women were sometimes prescribed strenuous activity in order to induce an abortion. Historians have found medical books that list recipes for herbal drinks that will abort a pregnancy. Today's methods of abortion are more advanced and the likelyhood of the mother dying as a result are greatly decreased.
In addition to researching the history of the subject, you may also want to research the laws and/or supreme court decisions that surround the issue. The case of Rowe v. Wade is a good place to start. Similarly, you should also visit the websites of organizations that are pro-life as well as those that are pro-choice. You want to be able to intelligently discuss all sides of the debate.