A great idea for the vow kiss is for the groom to kneel and give a gentle kiss to the bride's belly, a "kiss to the belly."
It represents the intention of:
"From now on, I will protect both of you."
"We will build a happy family with our soon-to-be-born baby."
It can feel like a declaration of intent, and if you want to announce that you're having a child here, it would be a happy surprise for the guests!♡
If the ceremony can be adapted, you could have the MC say something like:
"Bride ○○ is expecting a baby due in ○ month. A kiss of love is being given from the groom to the baby through ○○."
That could be a nice touch?
Impactful too♩
Taking pictures of kissing the belly in maternity photos is typical,
but surprising everyone with a "belly kiss" during the vow kiss of the ceremony was something I had never thought of...!
However, if all the guests know about the baby and you want to share it at that moment, I thought this method would be fresh, lovely, and a joyful time.
Doing it after a regular kiss on the lips or cheek is also nice.
When the baby grows up, it could become a cherished memory of the wedding that you would want to share♡