This is a really difficult one and it probably takes a huge leap of understanding and empathy on both your parts. It's also worth clearing things up with her sooner rather than later to stop this in it's tracks. It's amazing how much hurt this sort of stuff can cause.
It's not exactly the same but here's what happened to me. I miscarried twins in January last year (it was missed and so I found out at a scan, had to have ERPC etc). It was very traumatic and DH and I were devastated but tried very hard to be a bit stiff upper lip about it - probably stupid of us but we have a 3yo DS etc.
Five weeks later, friends of ours arranged for us (plus other friends) to meet for Sunday lunch where they surprised us all with the news that they were pregnant. I had to excuse myself in order to sit and weep in the toilets. I couldn't get out of there quickly enough. It was genuinely the most excruciating experience of my life. I was shocked by my own reaction, and completely mortified, as well as confused that they hadn't forewarned us.
That evening, DH rang them because we thought it would be better to face it head on, apologise for ruining their moment, and frankly allowing them the chance to apologise for not realising how difficult it would be for us. As far as we were concerned, the whole situation was just unfortunate. It wasn't anyone's fault I don't think. Just an embarrassing mishandling of a situation on both sides which needed responding to and putting to one side quickly. Unfortunately they were watching a film that evening and didn't want to speak to us. I was gutted and felt that they didn't care at all.
A little later, DH met with the guy from the couple, and they talked and sorted things out. The message from his partner was essentially that she was waiting for me to be ok, and to come and 'talk' to her about it. I felt that I had made an effort to sort it out and that it had been rejected.
To be honest, it all gets petty and silly from here. We were just no longer in contact. I was I suspect, still grieving, and angry with her for not recognising what was going on. I was happy not to have anything to do with her until she got in touch with me (told you it got petty). That didn't happen and there was also an unfortunate facebook misunderstanding (social networking has a lot to answer for). DH wanted me to resolve the situation though and so at his request, I emailed them both explaining how I felt and saying that I wanted to put it behind us and mend the relationship.
I received an email from her by return requesting that I never get in contact with her again. I responded saying that this was a ridiculous situation to be in and that I was offering an olive branch which wouldn't be offered again. And that was that.
Six months later, they've had their child. I'm days off having DC2. Our relationship has completely broken down and it haunts me and makes me rumble with anger. It's very difficult for DH and has impacted on our wider friendship group. We never see them now and have never (or are indeed ever likely) to meet their child, and they have no contact with ours. It's all a massive shame.
I hear things on the grapevine occasionally. She is apparently angry that I wasn't more involved in her pregnancy, and feels that I had some sort of agenda in emailing them just before my 12 week scan. I'm not sure what that would be other than to use my dead children as a means of getting some attention, but anyway!
This really isn't me trying to justify anything. I'm sure I haven't behaved perfectly in all of this. But the point of me telling this story is to say that if the friendship is important to you, mend it now. Be empathetic, and allow her the space to do the same. I've lost a friendship and have had a really terrible experience made much worse. Fertility, pregnancy, parenting, are all massively emotive issues. Who's to say who's right or wrong. This is not something either you or her can be objective about. You just need to put it to one side and move forward.