The relationship between these concepts can oftentimes be explained by human Geography and the stages of development of a country.
We measure the development of a country with the Human Development Index (HDI). Check out this video on how we measure poverty to understand the HDI a bit better:
Now, what is the link between poverty, ill-health, high population density etc. and how does this link back to development?The countries of the world are moving through the same stages of development (called the demographic transition model). According to this model countries with lower stages of development often struggle with high rates of poverty, overpopulation, poor medical care, etc. Luckily, countries are moving towards a higher stage of development, with improved education, medical care and higher standards of living.
To learn more about the demographic transition model and how these concepts are related to each other, check out this video: