In most MEDCs population growth is stable. MEDCs have low birth and death rates. In some Germany the birth rate is actually lower than the death rate. This means there is a decrease in population or a natural increase of -0.1%.
The major problem for many MEDCs is an ageing population. Life expectancy in MEDCs is increasing as people are now living longer due to improvements in health care, diet and lifestyle. Therefore, there will be a a greater number of elderly dependents. In the UK this is likely to lead to increased taxes to pay for health care and pensions.