People assume I'm on a second marriage when they I say that I have an eleven year-old, too. It's not that I even care what strangers think, but I know I'll have to deal with this, so I've been practicing different responses on random people in the checkout line.
1. The straightforward answer: "We kept trying, but I had a lot of miscarriages. This one took $38,000 of high-tech intervention."
The thing is, if you're that point-blank about it, you're pretty much opening yourself up to a lot of follow-up questions. Which could be good, if you feel like being the infertility ambassador and maybe counteract the myths about relaxing, etc. But it's hard to have that information out there amongst, say, the parents of your kid's school. Gossip can be vicious - and if your kid has any kind of quirk there will be rumours about how he was an IVF baby and maybe that explains why he's so (fill in the blank.) Believe me, even people I generally like have accidentally made comments about "only children" in front of me - always followed by a disclaimer that my child was of course an exception.
I've heard other parents mention only children, adopted children and single-parent (as in true single parents, not divorced) children in pitying tones. The thing that sucks is that even if only a few people that would even think of commenting on something like that, it becomes a part of the child's gossip-resume among the other parents. I barely knew one mother but had heard for years that her daughter by a sperm-donor had "identity issues." Another mom was commonly referred to as "one of those older parents with an only child." What does that even mean?
2. The shock-value response: "Yeah, it took us a while - I had to get over my tendency to have spontaneous abortions."
Shock is always good for getting people to just shut up. Most people I know are pro-choice, but the word abortion is a conversation stopper anyway. Good for if you just want to get away. Again, maybe not the best choice for parents at school...
3. The vague explanation: "Well, things don't always work out exactly like you thought they would."
If you can pull this off without adding any platitudes about how things are "meant to be" or whatever, it might let the other person know that prying is often considered rude, and maybe it's time to change the subject. The worst part of the vague answer is that it implies that the pregnancy was an accident, and given the truth about pregnancy after 40, I hate to contribute to that idea.
4. The deflection: "They say things happen for a reason."
Also vague, but buys into the demand for some kind of grand scheme for our happiness. People seem to like that. It's disingenuous, though, because the implication is that the reason has some reflection on our lives or our worth, and I hate that idea even if I'm just saying it to get out of a longer conversation. I can't believe in any kind of "reason" that has put the women I've come to know through the years of heartbreak infertility can cause.
In general I hate the idea that we aren't to a larger extent masters of our own destiny. I do blame myself for letting years for letting so much time go by without demanding better explanations for why I wasn't getting pregnant. But even women who do get thorough treatment and better options than I did can spend years trying to find success. That's why I don't like the idea of "working hard" to get a baby - it isn't fair to someone who has tried IVF again and again, gone to the best clinics, changed lifestyles, undergone surgeries and still doesn't end up with a baby.
I wish it hadn't taken me so long to figure out what secondary infertility even was, and that it really was a problem for me. I wish my kids weren't going to be growing up in practically different generations. I'm still mad at myself for letting so much time go by before I realized that I needed an aggressive clinic and a heavy-duty treatment. A lack of information and a lot of confusion about infertility is probably why it took me so long to figure it out on my own - so why is it so hard for me to just be honest about it when other people ask?