Oh yeah and by the way dreams mostly mean something completely different from what we think they mean. Try and self evaluate yourself, and you just might find out what the dreams mean.
God is always trying to speak to us. Sometimes birth means death and death means birth. A baby boy could mean, a brother or someone lower than you---like nephew or something. Her dreaming of you having baby could mean you are on a journey of re-birth or a new birth of something in your soul. Or the boy meaning your husband or boyfriend is on a journey of a new birth, or rebirth in his soul. Possibly your love will give him a new birth, your sister being the love. There are so many possibilities, within a few days I usually always know what my dreams mean. And others dreams for me. She could also be dreaming of herself, so many times when we dream of someone so close, sister, mother it coulld mean ourself. The part of us that's like them!!! She might soon be expecting--or it could mean exactly what she dreamed and it just hasn't happened yet. Or it is a warning to you to keep careful, if you don't want to be pregnant right now. Like I say so many possibilities!!!
But I am a self evaluater and I think, think, think, about things. Some might say i'm obsessive.
Just a few ideas for you