Help! Need a book recommendation!

L D

The kids are thrilled about having a baby.  They are also staring to ask me how the baby is going to come out.  Landon asked me if I was going to die.  . He was rather scared when he asked so I need a book to help explain it on their level.  It can either be one for me to help me find the right words or one for them that would help understand how a baby is born.  I'm sure this will also lead into how a baby is made/ how the baby got in my tummy to begin with.  They are 5.5 & 6.5 yrs old.