I've just come back from work and checked on how my villagers are getting on. I saw that they'd amassed enough tech points to reach level 3 in Fertility, so I should be able to get the GC next. After spending the points, I found that the population is maxed out at 90, and there are no mothers with babies. I suppose I'll have to wait for someone to die before another baby gets born. However, the oldest villager is only 58.

Unless someone knows of a way to bump off a villager ...

Nope, that is a common problem. Just have to wait until someone dies, or a special event that will make your population go down.