That is only said because all surgeries have risks. If you do a surgical abortion with D&C there is a risk of them scarring the lining of the uterus preventing future pregnancies. This doesn't happen often, unless as already stated, you have numerous abortions. However, if you plan to have it done, please go to a reputable place. Make sure you ask a lot of questions about the procedure, the doctors, cleanliness, and post care.