To tell my bro his wife is secretly preventing pregnancy?

He deserves to know she doesn’t want children. She is being very selfish

I would speak to her first, tell her its unfair of her to put that on you..... and that she needs to tell him. That you will give her that opportunity, but give a time frame.
I would not want to be told a secretive that.
I think this betrayal is as bad as saying you are on contraception when your not...... because although yes its the woman's body. They are married and she is taking a choice away from him in an untruthful way.
A hard conversation needs to be had, whether its she doesnt want chikdren right now, or she never wants children. But she needs to let your brother make an informed choice

Yeah right.

She could just have started an anonymous thread on here. I wonder who the friend will tell? After all, as you say yourself "There is a massive mental stress involved keeping secrets"

And the friend now knows something that it was life changingly important that I know.

I’d have gone straight to my best friend as well. The OP has been unfairly put in a massive moral dilemma- she absolutely should seek out an independent party to help her work out what to do. There is a massive mental stress involved keeping secrets.

I’m close to my brother- i absolutely would tell him no question. If the roles were reversed I would be devastated to find out he knew something that it was life changingly important that I know.

Totally agree its her body and her choice, but its not the point, she's lied to her husband!

You're coming from the mindset that talking about TTC is cringe and it should be secret/hidden.

If the brother and SIL wanted it it to be confidential, then I agree that it's bad form for OP to share with a friend.

However, if they don't mind who knows, then it's fine for OP to share. I have a friend who has told a lot of people about her struggles with IVF, for example, and doesn't mind at all if people discuss it. I myself shared with family that I was TTC and wouldn't have minded if they talked to others.

So very much depends on the people involved.

Just to confirm, is your bro, your actual brother? If so, definitely tell him! Your loyalties are to him rather than SIL.
also shame on your SIL for putting you in this position. It’s also really cruel what she’s doing to your brother

I'd tell him, that's horrible of her to pretend to be trying for a baby with him when she knows she's on contraception. If she doesn't more children that's fair enough but be honest about it and don't let him have that heartbreak month after month when there's no positive pregnancy test. He's your brother so your loyalty should lie with him and you should tell him and then it's up to him what he decides to do.

I would tell her that I wasn't prepared to keep that secret and that I would tell my brother.

The OP hasn't kept it secret. She's blabbed to her friend about it. I seem to be the only poster who thinks the OP lost the high ground there- cares so much about her brother but happy to gossip about him behind his back.

Absolutely, poor guy. Is he minted by any chance?

I think you should tell him, he's wasting his life on someone that is denying him something he really wants

So if anybody tells you anything about their medical issues, sexual health or reproductive choices and specifically said it's in confidence, you think it's OK to go tell anybody you feel like? Or is it just for women who aren't fulfilling their womanly duties in producing children even when they don't want to?

And if a man was in a position to do this to a woman? Despicable behaviour. I would tell my brother. If she has shared the information that is her problem.

You could just say your wife made a comment to me I’m not sure if she was joking or not then just say to him she said she’s on the pill. Then it’s up to him to decide what to do. This would make sense to why she is refusing medical tests though. If she’s lying to you that’s better than stringing your db along. Blood is thicker than water your loyalty is to him not her. If she’s being serious she’s being selfish letting him think it’s not happening when she is deliberately making it so it can’t happen.

yes. something like this...

What your SIL has done is let you know, probably in the hope that you may say something to him so that she doesn't have to. Its very immature of her.
Did she say why she didn't want children? Is it a case of she'd rather wait a while? Does she have time for that?

What a horrible position to be in. Especially if when the cats out of the bag she will probably tell him that she'd already told you.

She needs to talk to him.

This.

OP, personally I’d be pushing SiL to tell bro before you do. That’s not ok.

Very often in families people set traps. Can you be sure she is avoiding pregnancy?

She could be saying that, just to see if you will tell your brother!

You must tell him. If you don’t and he finds out you knew (and she surely will tell him you knew if her back is against the wall) it will destroy your relationship. Imagine your sense of betrayal of the situation was reversed.

And yes, he should divorce her.

I wasn't the poster who first described it as creepy- so perhaps you could take the point up with her.

I do however think that creepy might not be the wrong word for the OP's inappropriate gossiping with her friend.

Where did I say everyone was like me? I said that creepy was an odd word to use - like there’s something sinister going on. I was merely pointing out that some families talk about things like this and there’s nothing wrong with it.

This is so weird that I think I would just tell your DB what was said and how. Say you have no idea whether she was joking or hoping you would pass the message on to him or something else, but this is what happened, and you have literally nothing else to say except that you were puzzled. Then it's up to him what he does.

"Loyalty" isn't a word I'd use given OP has blabbed to her best friend about this.

Why do you think everyone is like you? "Creepy" wasn't my word. I initially agreed but it's not the right word. I find anyone telling me "they are trying for a baby" / trying to make that happen toe curlingly twee.

I would have told him straight away. My loyalty would be to my brother 100%, not to some deceitful bitch.

Your loyalty is to your brother in this case. He has a right to know and decide what he does or doesn´t want to do.