You've probably seen the articles going around about how Apple and Facebook (as well as other hot tech companies) are offering egg freezing coverage for their female employees in order to "free" them to focus on their careers while young without giving up the chance to have a family. There are moral and medical problems with the increasing consumerization of human reproduction. Freezing eggs may get around certain issues related to age-based infertility, but it doesn't change the fact that the human body is simply older when you're in your forties or fifties, and pregnancy is hard on bodies. At the moral level, this is yet another example of our modern culture seeking to bend humanity in order to "have it all", in this case treating children as something we deserve to have on our own timetable, even if that means completely separating sex and reproduction.
I have to wonder, though, if this even makes sense on its own terms. The theory is that people will want to be totally focused on their careers in their twenties and early thirties (when it's easier to reproduce in the way that worked for grandma, grandpa, the birds, and the bees. And yes, all other things being equal, taking a couple of three month leaves (and making sure you get off work right on time so that you can pick your kid up on time at daycare) can slow down your promotion path a bit in your twenties and thirties.
However, in most people's careers, even among those that make it into executive management, their twenties and thirties are times when they can more easily afford to go slow than their forties and fifties. Yes, we've all heard about the wunderkinds who found companies at 20 and are leading billion dollar companies before their thirty. However, the number of people who do that is about as small as the number of people who are composing violin sonatas and symphonies in their teens. Most people who make it into the executive offices don't hit the vice president level until their forties, and don't hit the C-suite until their fifties. Nor does this only apply to those with exalted careers. Pretty much across the income spectrum, on average people have their highest earning years in their fifties.
So even if you're thinking of this issue totally from a career point of view, it seems like you're more likely to miss out on important career opportunities by taking time off to have kids unusually late, than you would doing so at a more natural time of life. At thirty to thirty-five, which in these late marrying days seems to be when a lot of people in the upper middle class are having their kids, your peak earning years are still twenty years off. Taking things slow for a few years probably won't have as big an effect as doing so ten or fifteen year later.
Why then this idea that you should be utterly focused on your career at these comparatively young ages? I think it's in part significant that this is coming out of tech companies, which tend to be younger (at least in image if not in actuality), but even more widely there seems to be an excessive focus among the ambitious on a script that most people simply don't follow: the brilliant young success story who makes it big at a very young age.
Perhaps part of the problem is that, when we're young, we're not very good at thinking about the future. Just a year or two away seems like forever. Certainly, I know that when I was twenty-five thinking about goals for five years in the future seemed like thinking way, way down the line. Five years away, why I would be old then. I'd practically be nearing the end of my career. I wanted to know what I needed to do right now, this year, to advance at work.
But while people who are wildly successful while still very young make great stories, and thus are the focus of an inordinate share of the news articles and business biographies that you can read, their stories are interesting precisely because they are the exception rather than the rule. It's normal to be impatient when we're young, but it would help if people at least heard a bit more in their twenties and thirties what a normal career path normally looks like. For most people, you're laying the groundwork at that age: getting into a line of work that you're good at and building some expertise. The biggest years for you are still a long way off, even if you work at Apple or Facebook. Chill out and have a kid the natural way, rather than telling yourself it will somehow be easier when you're fifty. If there's one thing that is absolutely not going to be easy for anyone it's running after a toddler in your fifties and dealing with a high schooler in our mid to late sixties. There's a reason why nature has you reproducing while you're still comparatively vigorous.