I have no regrets for having had my kids during grad school. As I wrote previously, now that they are in their elementary years, parenting has gotten so much easier.
This isn't to say that there aren't perils. I don't mean the mere sick day here and there or cobbling together day care for the summer or random days off from school. I'm talking real heartbreak.
It is the nature of an academic career that it is a nomadic life. You get your PhD and you move. Three years later, you finish your postdoc and move. Repeat until you land a permanent position. Given that the average time until this happens is at least six years, and is probably even longer these days with the poor economy, it's an awful long time before you can really settle down.
The two-body problem is hard enough. When you have kids, it becomes an N-body problem, which is known to lead to chaos.
I've been fortunate in being able to spend all of my postdoc years in the same area, so I haven't had to move since for the last seven years. But now I am facing the prospect of moving clear across the country to another state. For my astronomer friends, this is par for the course. Our turbulent career paths aggregate us together for a short time before the next eddy disperses us again, only to form new aggregations elsewhere. We are sad to part, but know that we'll see each other again, if only at the next AAS Meeting.
When you have kids, though, you become a part of the local community. You become invested in the local schools and their PTAs. You make friends with the parents of their friends. You sign them up for team sports. You might even start taking karate lessons along side them. You become involved in scouts, and your spouse becomes a scout leader. When the other parents hear that you're looking for jobs on the other side of the country, they tell your spouse, "I know it's the best for her career, but we really don't want to lose you! Don't tell her I said that."
I have made very good friends here, friends that I can't count on seeing again at conferences. My kids and husband have made friends here, too. We have become a real part of the community here. Now that moving away is becoming more and more of a reality, it's become more and more heart-wrenching.
I know that given the job market out there, I should be grateful just to have the opportunity to stay in astronomy. It's just that it doesn't come without some personal costs.