YOU SAID:

my sister is pregnant im going to be a dad

INTO JAPANESE

私の妹は妊娠中のイムはお父さんになるだろう

BACK INTO ENGLISH

My sister will be pregnant Im will be father

INTO JAPANESE

私の妹は妊娠しますImは父親になります

BACK INTO ENGLISH

My sister gets pregnant Im will be a father

INTO JAPANESE

私の妹は妊娠しますImは父親になります

BACK INTO ENGLISH

My sister gets pregnant Im will be a father