Most women grow up believing their purpose is child-raising and family-making. Even if she wasn't indoctrinated like the rest of us, it's definitely a sore spot for a lot of us as we get older. Please, please be genuine in your apology attempt. This isn't like accidentally scratching her car when you borrowed it, you've essentially repeated something negative she's likely been hearing for a long time.

It's really hard not to internalize fertility issues.