The four major factors affecting your chance of getting pregnant are:
If each of these four factors is OK, then your chance of becoming pregnant in each ovulatory cycle is about 25-30%. Your chances are lower or even zero when even one or more of these factors is abnormal. About 50% of couples get pregnant within four to five months of trying to conceive, about 75% of couples will conceive during the first eight months, and up to 85% of couples will conceive within the first year of TTC. The ability to conceive in any given cycle falls after age 30. Keep in mind that with irregular menstrual cycles it may take longer to conceive because it's harder to figure out when you're ovulating. If you haven't got pregnant after a year of trying (six months if you are over 35), you may want to talk with your doctor about your options.