Governments and corporations would like there to be more people. More people means more money flowing about, and more power to be had, and everything just goes faster. Environmentalists would like there to be less. More people means more used resources. More displaced wilderness as we require more cities, more farms, more mining, more everything. And both sides would, I imagine, like to apply pressure. Most famously, earlier this week Iran's government suggested dialing back the marriage age as a way of encouraging growth.
I think a major factor in people's decisions about reproducing are about resources. Not the biggest factor. The biggest factor is personal attitude towards reproducing. Someone who thinks it's their duty to God to have more children will have more than someone who thinks it's a burden on the Earth's ever-dwindling resources. But resources plays a role too. When food and toys and housing and education are expensive, and work opportunities are few, children are going to feel like a luxury that one just can't afford. One feels that any children one brings into the world will be living a life of deprivation and want, never sure where their next meal is coming from.
Or, even connecting couples can be a problem. In societies that strictly segregate men and women, men and women tend not to know each other very well. One may want to start a family, but in this kind of society, one has no idea how to go about doing it. Maybe you could talk to your parents or friends about it, and maybe someone knows someone who knows someone who you can hook up with, but it does make it far less likely. And even if you do manage to meet, you're so unfamilar with each other's upbringings that you may very well develop a relational train wreck. In other societies, people are so shy that they don't connect well. It's hard to want to marry someone who's afraid to hang out with you, or tell you what they're really thinking.
So, should society encourage more or less reproduction, and if so...how?