Likely, your daughter is upset that the baby isn't going to the part of her family that she thinks should have a baby. Let her know that you're okay with it, that you'll have a baby when it's time, and that all babies are blessings. She should be fine.

sometimes, despite the fact that their parents marry other people after a divorce, kids still hold out hope that their "parents" will get back together.  You might find that the new baby her Dad and step Mum and having has made the reality of that not happening hit home for her.

When I fell pregnant with my first child my stepdaughters were initially excited, then the eldest became a bit withdrawn.  I asked her what was wrong and she eventually told me that she was scared once her Dad had a new baby there would be no time or love for her!  Poor little angel.  It made me cry and we hadn't considered that his girls might feel like that!  I asserted that she was Dads' first child and even if he had 100 more, no one would ever take her place in his heart as becoming a parent for the first time is a huge event, never to be forgotten.  We talked more about why her Mum and Dad didn't love each other, and I explained that it sometimes happens, and that there is a big difference between being "in love" with someone and "loving" someone.

Thankfully we have weathered the storm of blended families, and shared many parties, BBQs and family get togethers over the almost 18 years since I met my partner.  I call my stepdaughters "my big girls" and they have a very close and loving relationship with their younger half brother and sister.  My stepdaughters are now 21 and 24 and we are very close - sometimes I am even surprised at what they share with me!

There are so many angles to consider and the other replies you have been given here offer more insight than just my experience.  I think the most important thing though is that you need to gently get her to talk over her feelings with you and tell her that her feelings and fears are valid - even though you will probably find they are way off the mark.

All the best - it's a tricky one but I'm sure you'll get through it and she will be fine!   Sharon

While no expert in child behaviour, I feel that your daughter is upset that it isn't you having a baby first. 

I'd be sitting down with her and saying that her step mums baby is still going to be her brother/sister, because they will share the best parts of her dad with her, just like when you have a baby it will be her brother/sister because they will share the best parts of you with her.

Without being to graphic, explain to her that it takes time to get a baby in your tummy.  Tell her about how long it took for her to be in your tummy.  If she understands that it doesn't just happen, then she might relax a bit more about the whole thing.

Another possibility for her disappointment could be the fact the her Dad doesn't live with her any more, and him having a baby would mean she has to share him with the new sibling.  He needs to explain to her that he will always love her, and that his love grows with every new child, because seeing the other children with the new baby makes him happy.

Good luck, and I hope you are pregnant soon, because that will make it easier on her too.  Have fun with the trying

It's entirely possible that your daughter wants 'her parents' to have a baby, and that she views her stepmother as 'not my parents'. You're her mother, and she's happy to have a sibling through you but that she views her father's partner as not quite the same. She may possibly view her stepmother as 'not quite the same' and feel far less ownership of that baby that she would from one of her own birth parents.

I think you should ask her how she feels about her stepmother's baby, and ask why she feels the way she does. Let her know that it's not bad, to feel one way or another, or threatened, but that talking will help. Getting to the root of the problem may go a long way towards helping to overcome it.