I’d say terrible state of child care might be one of the reason for not wanting kids: short maternity leave and extremely expensive day care options could kill a desire to have kids. It’s not affordable. Even in countries with longer maternity leave, day cares are too expensive and it’s not affordable to live on one income. Plus it’s not realistic to leave your job for a couple of years and then just roll back in. In some industries you are going to be 100 steps behind if you stay home longer than a year

But many people nowadays don’t want kids for variety of other reasons, not just the cost. My daughter has several married friends in their 30s and they have no desire to bother with having kids. It’s getting more and more common to make that choice.