Congratulations on your baby note

My male coworker just had a baby.
He gave everyone in the office a gift.
Is this common?
I’m from the US and usually it’s the other way around.
We would give him a gift and he might give a thank you note.

I’m not sure how many days he will be out of work with his wife and new baby.
So I would like to leave him a note that says congratulations.
Can someone tell me some typical phrases in Japanese?
Not in romaji please.

I don't think it's a common aspect.

sample message:
ご出産おめでとうございます。可愛い家族が増え、ますますにぎやかで楽しくなりますね。赤ちゃんの健やかな成長を心よりお祈りしております。

Congratulations on your new born baby.
It will be lively and fun to join new member in your family.
I(We) hope baby hood is filled with lots of happiness and healty.

In Japan, the parents are usually given a gift first, and then they will give back a return gift.

Are you new to the workplace? Maybe everyone had paid money and had given the new dad a gift before you arrived. Or if the dad was giving away very affordable gifts, maybe that was something like the cigars that new dads used to give away in the U.S.

Either way, that's nice of you to give him a small note of thanks :)