How to tell a friend my sister has given birth to a baby boy

[Lenamithu]

Conversation with a friend after a long time

How to tell a friend my sister has given birth to a baby boy

 

[emsr2d2]

I was having a conversation with a friend after not speaking to them for a long time.

How to can/do/should I tell my friend that my sister has given birth to a baby boy?

You've almost answered your own question. You can say to your friend "My sister has given birth to a baby boy".

 

[Skrej]

A slightly more natural version would be something like "My sister had a baby boy."

 

[emsr2d2]

Frequently, we don't even mention the sex of the baby in the first instance. You might say "My sister has had a baby". The other person is likely to say "Girl or boy?" and then you can give more information.

 

[probus]

Further to emsr2d2's comment, there are people nowadays who refuse to assign their baby to one sex or the other, and other people who decline to disclose that assignment even if they have made it.

 

[Skrej]

Of course, you could always say "I'm an uncle now", if you want to make it about yourself and not your sister.

If this isn't your first niece/nephew, then "I'm an uncle again."