Hmmm, the Chinese herbalist in the Boston area might be worth a try that someone else suggested. I know you said she's tried adoption and struck out. But if having a child is truly what they want, adoption may take a while, but it can come to a wonderful end.
My best friend in Chicago did an open adoption. It's not for everyone and has some pitfalls, but it has been wonderful for them. They were actually at the birth! The birth mom had him for a few days/week to give him the benefit of the her first milk supply and to say goodbye to him. It was nerve-wracking, wondering if she would change her mind, etc. But it all went as planned.
He is now 13, has periodic contact with his birth mom and birth brother (a couple years older). It has been very helpful to have a loose affiliation with the birth family. It helps them see development, learn about health issues or quirky behavioral things. And helps him to have a brother to connect with on occasion.
It was hard at first because the birth mom wanted more of a relationship than my friend wanted. One time when the birth mom was going to check herself into a mental health facility, she just called and said can you take the older brother? They took him but then had to draw the line more clearly. They weren't her babysitting service. They were prepared to try to adopt the other son, if things continued like that, but it never happened again. They now have much better boundaries and it works well. Sometimes, they have the brother over for the weekend but mostly they have their separate lives. And the weirdness has passed. Their son is definitely their son, not the birth mom's
alternate mom like a step-mom situation.
Like I said, it's not for everyone, but it has been a huge blessing to all involved.
As an aside, I'm afraid I have no ideas of how to console someone who is struggling with not having kids. My friend and I both have just one child--hers adopted, ours after 9 months of trying. Both of us are delighted with the one, but will always feel the loss of not having another. For the most part it doesn't bother us any more, but time was the best healer.
Our 13-year-old used to pine over not having a sibling, but now he hugs us and says he loves our little family (especially after being at a friend's house with "annoying" brothers or sisters around).
It's hard walking in another's shoes. Asking her what she prefers can be helpful. Just know that some people can live through the joy of others and accept their fate. Some can't or take much longer than you'd expect.
At our church, we used to help out at the nursery long after our son was in it. It was fun to see the little ones, even if we didn't have another. But I realized I had to stop doing that at some point because it kept the wound open of not having a second. I was surprised that 5+ years down the road, when I thought I was over it, I would get teary on occasion about it still.
Time is a wonderful healer. Checking in with your friend, doing things with her, and not always talking about your child can help. But don't always not talk about your family, either. She may love hearing about your little one...or not. She may be able to tell you what helps the most. But remember that may change as time goes on so be attentive to her growth through time.
It's sad to say, but sometimes friends diverge when one has kids and the other doesn't. It doesn't always happen, but sometimes it is a natural progression. As long as you both are true to yourselves and to your friendship, it will evolve naturally--sometimes awkward, sometimes not.
Good luck!