For as long as medicine improves, for as long as birthrates fall, there will be problems with the demographic breakdown of developed societies. There are not enough young people to pay for society's old ones as it stands, and it's only going to get worse. Nobody wants to blame greater life expectancy, since it seems churlish to go to all that effort to prolong life, only to then complain about it. Instead, people point to the falling birthrate. In the past this has caused some rancour among childless women, who get blamed for this when in fact women who have children, but opt to stop at two, are by far the more statistically influential group.The Institute for Public Policy Research has characterised the problem as a "baby gap" - women want to have children sooner, and more often, than they do. If maternal desire were satisfied, instead of deferred for the sake of careers, an extra 90,000 babies a year would result. However, owing to the maternal pay gap - which means that a woman of 24 on a medium wage would, should she become a mother, earn &pound;564,000 less over the course of her career - women are putting it off. Sometimes this scotches all chance of becoming a mother; more often, we just have to trim our families down a little.So far, so straightforward - what doesn't seem to be straightforward is the connection between whose pay packet is affected, and who makes all the decisions. We are constantly told what women want, vis-a-vis childbirth, what our priorities are, where our thinking is flawed, which mistakes we're making, how our behaviour affects wider society, and which section of us is driving the trend towards geriatric motherhood.It is absolutely illogical to assume that, just because women do the gory bit at the end, we are in charge of the decision to set the whole business in motion. There are, of course, women who go it alone, banditting sperm from unsuspecting males whom they then screw for cash via the Child Support Agency. These women crop up a lot in execrable radio drama, but very rarely in real life. There are women who end up doing it alone, but this doesn't necessarily mean they decided to have children unilaterally.Pending a more in-depth survey, I imagine that people approach having children the same way they would choosing a holiday or a sofa: in some couples the woman will hold sway; in others, the man will. In lovely, healthy couples, all decisions are made jointly and Relate never gets involved. If people are having children later and later, this must be as much a reflection on what men want as it is on what women want. Lots of you could probably offer me case studies about this or that woman who refused tenancy of her womb for her 20s and 30s because she was having too much fun or earning too much; but for every one of them, there'll be another who was badgering for children from the word go, dismissing financial considerations with a nonchalant "What do babies need? Love and milk!"And yet we never discuss this as a social trend. Generally, we discuss it as a female trend; just as we never discuss childcare in terms of the damage wrought by "working parents", only by "working mothers". The process of reproducing is always collaborative when it's going well; the fault of women when it isn't. It's so glaring, I'm always amazed that people think they can get away with it, and yet there it is again in reports that "work pressures force young women to shelve plans for a family". From the Observer!Having children is almost always a joint decision; a maternal pay cut is almost always assessed in the context of two salaries; men are invariably involved. This isn't something they're suckered into while they're trying to watch the football.