영어 문장 네 개 해석 부탁드려요

아래 영어 문장 네 개 해석 부탁드립니다.
1. It is ironic, then, that for more and more developed countries the main demographic challenge is not overpopulation, but a declining one.
2. In addition to health-care issues, Moscow-based journalist Oleg Glebov claims the overall state of depression following the break up of the Soviet Union is a key factor in the declining population.
3. Things may not be so gloomy in western Europe, but nonetheless couples are still reluctant to have children, with Germany, Spain, and Italy having the lowest birth rates in all of Europe.
4. Rising levels of education and prosperity, increased female presence in the workforce, and birth control are the leading causes of low birth rates in western Europe.