In our world our species as a whole tends to have a bias towards making children... or at least having sex which tends to lead to children. Some people have lesser drives towards sex, some people have stronger drives towards other things, but in general if someone decides they dont want to have kids that is generally up to them.
In this world men are pretty similar. We can be pretty horny, and without a good way to detect whether or not they've impregnated someone there isn't much difference. However for women things are a bit different. childhood development is basically the same. Early teenage years are pretty similar as well, late teenage years are only usually similar, and early adulthood may be similar. You see the term "biological clock" is a bit different as a woman's body in this world can sense that it hasn't had any kids. In the early years the biological clock isn't as active as their body is still growing and getting used to it's pubescent changes. However when the growth starts to slow the clock starts ticking. Usually not much happens at first, but at some point a woman's body isn't happy that it hasn't given birth and will start to signal some changes in their body. Their hips will widen, breasts will grow, and their sex drive will increase. At first the changes are minimal and tend to just get the woman in the mind that they may want to find a mate. However the longer and longer their womb is without baby the changes will get more and more pronounced. Generally when a woman's breasts are the size of watermelons they're in a special ward because they've just raped several men. After being impregnated a woman's sex drive resets to normal levels, although their breasts and hips tend to only shrink just a bit (most think this is just a lessening of blood flow though).
After the first baby about half of all woman don't have another "biological clock" period, but the other half do and usually the clock ramps up a lot faster than the first. After the second or sometimes third baby the "biological clock" phenomena tends to stop, and when a woman usually reaches menopause then the phenomena WILL stop. So whose story are we seeing today?