I think, there can be the basement of pressing. As an example here could be social networks, where people share their life to others, and other had to be better than first one. So there can be the pressure of economical situation of some persons, and also the pressure of lower self-esteem.
If there are a lot more females then males in a country, there could be a rise in births, and if it is serious it could lead to an overpopulation problem. If there are more males there could be a lack of births, and the infrastructure could be compromised. In both cases specific gender-related jobs could be in short supply or there might not be enough workers for a steady economy.
Large cities because there are more Job opportunities.
