How can I tell my child their older sibling died before they were born?

Ask them to sit because you need to talk and say just that! It will hurt and they'll want to know all about them, which you should absolutely let them do! Show pictures, tell them stories, etc!

I think talking about death of somebody to a child needs some maturity of the child's conscious. i think this issue needs to be addressed at an appropriate age, and choice of the talking moment should be, when the child him or herself needs to know, or, when the child is aware enough to understand that some kind of sorrow stems out of life of everyone. The child should remember thereafter what has been told to him/her.

Whenever you feel like they are emotinaly stable enough to handle the news, this could be today, tomorrow, next year, 20 years. You can gauge it by how they deal with other negative situations and how they deal with emotions

This is a tough question, and I think you need to wait until they're at least 12-13 before breaking the news (or whenever you think the child Is ready). I am so sorry that this happened, and no parent should ever have to explain something like that. The fact you've kept this a secret means that you are a good parent sweetie. Most parents I know have made the younger child live their life like the older sibling they lost. By keeping the news, it might feel like the older sibling is being replaced; but just because they're gone, doesn't mean they're forgotten. You might want to start with telling them "they're not the first born." After that, tell them "they're not the only child" to confirm that your child wasnt the first born. Then, just say that before they were born, his/her older sibling, (name here) passed away. talk slow and try and answer any questions the child has, because this news would be shocking to any child. Sorry for you loss, my prayers go out to you

This is a hard thing to reveal and yet it is best coming from you. Knowing your child find the right time and place and be honest and direct.