Many women with mild endometriosis will conceive easily although chances of subfertility even for the mild group are higher than the background rate for age. Severe endometriosis can damage the Fallopian tubes and ovaries, and the adhesions that can come with endometriosis can also block the tubes. Your gynaecologist will be able to advise you on what to do about this. Don't try for more than a few months without getting advice.