Hi Sue and welcome.
When I was trying to have a second baby, I sadly had an early miscarriage and began to think that my son was going to be an only child. We decided to wait no longer and brought home our lovely golden cocker spaniel puppy to be his friend - 'Sweep.' Needless to say, the following month I was pregnant, so when my second son arrived, we also had an 8 month old puppy whose whole mission in life was to be as mischievous as possible. Very hard work, but she adored the baby and they learned to get into mischief together. She seemed to understand that she shouldn't hang around him when he was tiny and crawling around, so would sit in her basket with eyes full of longing, waiting for permission to sit by him.
I would never leave a child alone with a dog, no matter how trustworthy and well known they are to me. We have always had at least one dog, including a gentle giant long-haired german shepherd, who we called 'Nanny Jake' as he would accompany the children wherever they were, sit by their beds before they went to sleep, watch them having a bath, and they would rest their heads on his back when reading or watching TV, which he loved.
Dogs enhance children's lives and whilst I wouldn't deliberately bring home a puppy when there is a new baby in the house, it worked out ok for us. My basset hound 'Nell' goes to doggie daycare and has been playing with puppies this week - she is being prepared to be introduced to my little grandaughters in the next few weeks - they are 7 months old now and haven't met her yet. She plays beautifully with children, so I'm optimistic she will adore these grandchildren like the others.