Had sex without precautions past month, does pre-ejaculation can cause pregnancy? i missed my periods on 20th,pregnancy test result negative

Yes: Pre-ejaculation can result in a pregnancy. The good news is that in any given month of unprotected intercourse, the change of pregnancy is about 20%. If you usually have a period every month and you've missed your period, you might want to repeat the pregnancy test just to be sure or see your doc to have a blood pregnancy test. Best Wishes!