Elizabeth Nolan Brown writes:
We generally think it’s a good thing that women start having children a little later, and portray young moms as foolish. But then suddenly—it’s too late. It’s like there’s a magic window between—what, 26 and 34?—during which all women are supposed to have all children. Before that, you’re irresponsible or unrealistic; wait until after that period, and you’re clueless and vain. In some socioeconomic classes, the window of acceptable baby-making time is even smaller: When I got pregnant last year, at 28, a significant portion of my peers acted like I was nuts for considering having the baby at my age (I ended up miscarrying). But if I give it three or four more years, I’ll likely be hearing lectures left and right about my ticking biological clock. Realize this, Gen Y ladies: You’ve got a window of about five to 10 years (at most) during which you should be ready, financially and otherwise, to have all the children you want to have, and in a stable relationship within which to do so, or society is going to frown on you hardcore.What she's describing is the fertility-specific angle of the Window of Opportunity problem. (See also the tag.) While the exact age varies subculture by subculture, women go from being too young to settle down to too old within a matter of minutes. I mean, the way it actually operates is, most family and friends are saying "too young," and gradually the shift tilts to "too old." What's important is that there's never a case of it being just fine to do what makes sense for you, in your life as you're leading it. A woman who's met the right person and settled into her career at 24 is still a child bride. A woman who's 44 and not even interested in marrying or having kids has missed her chance.
Still, I think the window of opportunity issue and the fertility angle shouldn't be conflated. The latter has more of a rationale than the former. Fertility really does decline; pretending that this decline is a conspiracy invented by misogynistic evolutionary-psychology popularizers gets us nowhere. (But I agree with Elizabeth that women know fertility declines, and that when women fail to reproduce by 35, it's not to be all "I'm a Carrie" but because very real factors like the need for a career/a partner got in the way.) And women who (not unwisely) wish to reproduce only once partnered have that many years on the earlier end of the available biological window to contend with.
Cultural construction only enters into it insofar as young women are discouraged from considering the men they date potential serious boyfriends until whichever key age, at which point every unattached man must be considered for husband potential. The window of opportunity thus only enters into it insofar as women who are ready to have kids in their early 20s - who've fully settled into their adult lives, or fully enough - are under social pressure, not only not to have kids, but not to make serious commitments to a partner just yet, because 22 is so young.
Meanwhile, the window of opportunity more generally is about commitment to a partner. Specifically, a male partner. Women go almost instantaneously from too young for a serious boyfriend to too old to find a husband. But where are these husbands supposed to come from, if they are not the serious boyfriends of yesterday? And biology is not as central as all that - a woman might, at 22, be 100% ready to commit to a particular man, but not ready to have kids. And, if by 45 a woman is unlikely to be able to get pregnant with ease, she does not suddenly lose her capacity to partner with a man. Not everyone wants (more) kids, and not all kid-acquiring is biological.
So, in sum, we can on the one hand not deny such factors as, fertility declines, and all things equal it's for the best to have kids only once partnered. And on the other, not conflate women with female reproductive organs.