the anus is in no way connected to the vagina so there is absolutely no possibility to get her pregnant through anal. you do want to be careful however that you don't introduce bacteria into your penis by not using a condom. that type of infection can be quite unpleasant
She can not get pregnant by ejaculating in her butt. However, since it is so close to the opening of her vagina, you need to be carful that no *** gets or drips down to her vagina because then it can be possible to get pregnant (sorry that sounds gross, didn't know how else to word it).