The other day a friend I see a couple of times a month remarked how when I first told her I was pregnant with B that she immediately thought she'd never see me again - being older and childless I'm sure she's been witness to this scenario dozens of times, as I was even in my thirties. Turns out I see her more now than I ever have - because she's available during the day, loves my kid(s), and of course I do enjoy her company. I find I work a lot harder to maintain my friendships now - but this is due to a couple of unique circumstances: I don't work outside the home, so access to friends is my only way of being around adults, and there's no husband or partner to fulfill that need. I also don't want to become that woman who has kids and immediately drops all her friends.
I have to say, though, that I'm lucky that most of my friends now have kids. There are only a couple of hold outs. I could have been one of them, but went down a different path. I often think if I had been surrounded by a big group of perpetually single people I could hang out with and travel with and spend holidays with I may never have had kids...but where, after thirty or thirty-five, do those big groups of single people exist? People want to pair off, and most people who pair off want kids, and most people who have one kid want another. I had an "if you can't beat 'em, join 'em" mentality, and that worked for me. I hate feeling left behind.
I look at the people I spend a lot of time with now and realize with sadness that even some of them will fall away; once these kids start school, especially, that'll be a whole new crop of friends that will eclipse the old mommy & me group friends. The sort of random people I hang with these days may drift away as our children's lives become more complex.
One thing that will hopefully keep things a little more consistent for us will be the fact that I plan on not moving...ever. We moved many times before I was ten; until fifth grade I was in a new school just about every year, sometimes twice in a year. And for no better reason than my mother just couldn't stay still. I do feel like all that disruption early on had a major damaging effect on me. To this day I have hardly any friends that I made before the age of twenty; I so envy those people that have big groups of friends that they grew up with - it's like having a whole other family. I want that for my kids so badly I'd do just about anything to make sure they have it - same house, same school, same friends. In that one area I really do want to give them everything I never had.